diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 71a83ba6..26c20dd1 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -14,6 +14,7 @@ jobs:
       fail-fast: false
       matrix:
         ruby-version:
+          - '2.6'
           - '2.7'
           - '3.0'
           - '3.1'
diff --git a/lib/overcommit/hook/pre_commit/rails_schema_up_to_date.rb b/lib/overcommit/hook/pre_commit/rails_schema_up_to_date.rb
index 1f2de970..dafd31a1 100644
--- a/lib/overcommit/hook/pre_commit/rails_schema_up_to_date.rb
+++ b/lib/overcommit/hook/pre_commit/rails_schema_up_to_date.rb
@@ -35,7 +35,7 @@ def run # rubocop:disable Metrics/CyclomaticComplexity, Metrics/PerceivedComplex
     private
 
     def encoding
-      return {} unless @config.key?('encoding')
+      return unless @config.key?('encoding')
 
       { encoding: @config['encoding'] }.compact
     end
@@ -53,7 +53,7 @@ def schema_files
     end
 
     def schema
-      @schema ||= schema_files.map { |file| File.read(file, **encoding) }.join
+      @schema ||= schema_files.map { |file| File.read(file, encoding) }.join
       @schema.tr('_', '')
     end
 
diff --git a/lib/overcommit/hook_context/helpers/file_modifications.rb b/lib/overcommit/hook_context/helpers/file_modifications.rb
index 8d221ddc..00aaccc8 100644
--- a/lib/overcommit/hook_context/helpers/file_modifications.rb
+++ b/lib/overcommit/hook_context/helpers/file_modifications.rb
@@ -12,7 +12,7 @@ def amendment?
         cmd = Overcommit::Utils.parent_command
         return unless cmd
 
-        amend_pattern = /commit(\s.*)?\s--amend/
+        amend_pattern = 'commit(\s.*)?\s--amend(\s|$)'
 
         # Since the ps command can return invalid byte sequences for commands
         # containing unicode characters, we replace the offending characters,
@@ -24,11 +24,18 @@ def amendment?
             encode('UTF-8')
         end
 
-        # True if the command is a commit with the --amend flag
-        return @amendment if @amendment = cmd.match?(amend_pattern)
+        return @amendment if
+          # True if the command is a commit with the --amend flag
+          @amendment = !(/\s#{amend_pattern}/ =~ cmd).nil?
 
         # Check for git aliases that call `commit --amend`
-        return @amendment if @amendment = command_is_amend_alias?(cmd, amend_pattern)
+        `git config --get-regexp "^alias\\." "#{amend_pattern}"`.
+          scan(/alias\.([-\w]+)/). # Extract the alias
+          each do |match|
+            return @amendment if
+              # True if the command uses a git alias for `commit --amend`
+              @amendment = !(/git(\.exe)?\s+#{match[0]}/ =~ cmd).nil?
+          end
 
         @amendment
       end
@@ -67,22 +74,6 @@ def modified_lines_in_file(file)
         end
         @modified_lines[file]
       end
-
-      private
-
-      def command_is_amend_alias?(cmd, amend_pattern)
-        `git config --get-regexp "^alias"`.split("\n").each do |alias_def|
-          alias_map = alias_def.match /alias\.(?<to>[-\w]+)\s+(?<from>.+)/
-          next unless alias_map
-
-          alias_from_match = alias_map[:from].match? amend_pattern
-          alias_to_match = cmd.match? /git(\.exe)?\s+#{alias_map[:to]}/
-
-          # True if the command uses a git alias for `commit --amend`
-          return true if @amendment = alias_from_match && alias_to_match
-        end
-        false
-      end
     end
   end
 end
diff --git a/spec/overcommit/git_repo_spec.rb b/spec/overcommit/git_repo_spec.rb
index 08f3b585..128737c3 100644
--- a/spec/overcommit/git_repo_spec.rb
+++ b/spec/overcommit/git_repo_spec.rb
@@ -24,13 +24,12 @@
         end
 
         submodule = repo do
-          git_config = '-c protocol.file.allow=always'
-          `git #{git_config} submodule add #{nested_submodule} nested-sub 2>&1 > #{File::NULL}`
+          `git submodule add #{nested_submodule} nested-sub 2>&1 > #{File::NULL}`
           `git commit -m "Add nested submodule"`
         end
 
         repo do
-          `git -c protocol.file.allow=always submodule add #{submodule} sub 2>&1 > #{File::NULL}`
+          `git submodule add #{submodule} sub 2>&1 > #{File::NULL}`
           example.run
         end
       end
@@ -151,7 +150,7 @@
         end
 
         before do
-          `git -c protocol.file.allow=always submodule add #{submodule} sub 2>&1 > #{File::NULL}`
+          `git submodule add #{submodule} sub 2>&1 > #{File::NULL}`
         end
 
         it { should_not include File.expand_path('sub') }
@@ -179,8 +178,7 @@
           `git commit --allow-empty -m "Submodule commit"`
         end
 
-        git_config = '-c protocol.file.allow=always'
-        `git #{git_config} submodule add #{submodule} #{submodule_dir} 2>&1 > #{File::NULL}`
+        `git submodule add #{submodule} #{submodule_dir} 2>&1 > #{File::NULL}`
         `git commit -m "Add submodule"`
       end
 
@@ -284,7 +282,7 @@
         touch 'tracked'
         `git add tracked`
         `git commit -m "Initial commit"`
-        `git -c protocol.file.allow=always submodule add #{submodule} sub 2>&1 > #{File::NULL}`
+        `git submodule add #{submodule} sub 2>&1 > #{File::NULL}`
         touch 'staged'
         `git add staged`
         example.run
@@ -329,7 +327,7 @@
       end
 
       repo do
-        `git -c protocol.file.allow=always submodule add #{submodule} sub-repo 2>&1 > #{File::NULL}`
+        `git submodule add #{submodule} sub-repo 2>&1 > #{File::NULL}`
         `git commit -m "Initial commit"`
         example.run
       end
@@ -345,8 +343,7 @@
           `git commit --allow-empty -m "Another submodule"`
         end
 
-        git_config = '-c protocol.file.allow=always'
-        `git #{git_config} submodule add #{another_submodule} another-sub-repo 2>&1 > #{File::NULL}`
+        `git submodule add #{another_submodule} another-sub-repo 2>&1 > #{File::NULL}`
       end
 
       it { should be_empty }
@@ -368,12 +365,11 @@
 
     context 'when there are multiple submodule removals staged' do
       before do
-        another_submod = repo do
+        another_submodule = repo do
           `git commit --allow-empty -m "Another submodule"`
         end
 
-        git_conf = '-c protocol.file.allow=always'
-        `git #{git_conf} submodule add #{another_submod} yet-another-sub-repo 2>&1 > #{File::NULL}`
+        `git submodule add #{another_submodule} yet-another-sub-repo 2>&1 > #{File::NULL}`
         `git commit -m "Add yet another submodule"`
         `git rm sub-repo`
         `git rm yet-another-sub-repo`
diff --git a/spec/overcommit/hook/prepare_commit_msg/base_spec.rb b/spec/overcommit/hook/prepare_commit_msg/base_spec.rb
index ef635a48..616d6b8e 100644
--- a/spec/overcommit/hook/prepare_commit_msg/base_spec.rb
+++ b/spec/overcommit/hook/prepare_commit_msg/base_spec.rb
@@ -38,7 +38,9 @@
           contents + "bravo\n"
         end
       end
-      [Thread.new { hook_1.run }, Thread.new { hook_2.run }].each(&:join)
+      Thread.new { hook_1.run }
+      Thread.new { hook_2.run }
+      Thread.list.each { |t| t.join unless t == Thread.current }
       expect(File.read(tempfile)).to match(/alpha\n#{initial_content}bravo\n/m)
     end
   end
diff --git a/spec/overcommit/hook_context/commit_msg_spec.rb b/spec/overcommit/hook_context/commit_msg_spec.rb
index 058f1508..2aa68516 100644
--- a/spec/overcommit/hook_context/commit_msg_spec.rb
+++ b/spec/overcommit/hook_context/commit_msg_spec.rb
@@ -298,7 +298,7 @@
         end
 
         repo do
-          `git -c protocol.file.allow=always submodule add #{submodule} sub > #{File::NULL} 2>&1`
+          `git submodule add #{submodule} sub > #{File::NULL} 2>&1`
           `git commit -m "Add submodule"`
           echo('Hello World', 'sub/submodule-file')
           `git submodule foreach "git add submodule-file" < #{File::NULL}`
@@ -474,7 +474,7 @@
         end
 
         repo do
-          `git -c protocol.file.allow=always submodule add #{submodule} sub > #{File::NULL} 2>&1`
+          `git submodule add #{submodule} sub > #{File::NULL} 2>&1`
           `git commit -m "Add submodule"`
           echo('Hello World', 'sub/submodule-file')
           `git submodule foreach "git add submodule-file" < #{File::NULL}`
@@ -500,7 +500,7 @@
         end
 
         repo do
-          `git -c protocol.file.allow=always submodule add #{submodule} sub > #{File::NULL} 2>&1`
+          `git submodule add #{submodule} sub > #{File::NULL} 2>&1`
           `git commit -m "Add submodule"`
           echo('Hello World', 'sub/submodule-file')
           `git submodule foreach "git add submodule-file" < #{File::NULL}`
@@ -532,7 +532,7 @@
         end
 
         repo do
-          `git -c protocol.file.allow=always submodule add #{submodule} sub > #{File::NULL} 2>&1`
+          `git submodule add #{submodule} sub > #{File::NULL} 2>&1`
           `git commit -m "Add submodule"`
           `git rm sub`
           example.run
@@ -561,7 +561,7 @@
       end
 
       repo do
-        `git -c protocol.file.allow=always submodule add #{submodule} test-sub 2>&1 > #{File::NULL}`
+        `git submodule add #{submodule} test-sub 2>&1 > #{File::NULL}`
         expect(subject).to_not include File.expand_path('test-sub')
       end
     end
diff --git a/spec/overcommit/hook_context/post_checkout_spec.rb b/spec/overcommit/hook_context/post_checkout_spec.rb
index df1dccd2..50657c37 100644
--- a/spec/overcommit/hook_context/post_checkout_spec.rb
+++ b/spec/overcommit/hook_context/post_checkout_spec.rb
@@ -67,7 +67,7 @@
 
       repo do
         `git commit --allow-empty -m "Initial commit"`
-        `git -c protocol.file.allow=always submodule add #{submodule} test-sub 2>&1 > #{File::NULL}`
+        `git submodule add #{submodule} test-sub 2>&1 > #{File::NULL}`
         `git commit -m "Add submodule"`
         expect(subject).to_not include File.expand_path('test-sub')
       end
diff --git a/spec/overcommit/hook_context/post_commit_spec.rb b/spec/overcommit/hook_context/post_commit_spec.rb
index 5322a1f2..81758256 100644
--- a/spec/overcommit/hook_context/post_commit_spec.rb
+++ b/spec/overcommit/hook_context/post_commit_spec.rb
@@ -20,7 +20,7 @@
       end
 
       repo do
-        `git -c protocol.file.allow=always submodule add #{submodule} test-sub 2>&1 > #{File::NULL}`
+        `git submodule add #{submodule} test-sub 2>&1 > #{File::NULL}`
         `git commit -m "Initial commit"`
         expect(subject).to_not include File.expand_path('test-sub')
       end
diff --git a/spec/overcommit/hook_context/post_merge_spec.rb b/spec/overcommit/hook_context/post_merge_spec.rb
index 0621b695..aa89fa82 100644
--- a/spec/overcommit/hook_context/post_merge_spec.rb
+++ b/spec/overcommit/hook_context/post_merge_spec.rb
@@ -94,7 +94,7 @@
       repo do
         `git commit --allow-empty -m "Initial commit"`
         `git checkout -b child > #{File::NULL} 2>&1`
-        `git -c protocol.file.allow=always submodule add #{submodule} test-sub 2>&1 > #{File::NULL}`
+        `git submodule add #{submodule} test-sub 2>&1 > #{File::NULL}`
         `git commit -m "Add submodule"`
         `git checkout master > #{File::NULL} 2>&1`
         `git merge --no-ff --no-edit child`
diff --git a/spec/overcommit/hook_context/post_rewrite_spec.rb b/spec/overcommit/hook_context/post_rewrite_spec.rb
index 0d510c4a..d2f18f6e 100644
--- a/spec/overcommit/hook_context/post_rewrite_spec.rb
+++ b/spec/overcommit/hook_context/post_rewrite_spec.rb
@@ -101,9 +101,8 @@
         end
 
         repo do
-          git_config = '-c protocol.file.allow=always'
           `git commit --allow-empty -m "Initial commit"`
-          `git #{git_config} submodule add #{submodule} test-sub 2>&1 > #{File::NULL}`
+          `git submodule add #{submodule} test-sub 2>&1 > #{File::NULL}`
           `git commit --amend -m "Add submodule"`
           expect(subject).to_not include File.expand_path('test-sub')
         end
diff --git a/spec/overcommit/hook_context/pre_commit_spec.rb b/spec/overcommit/hook_context/pre_commit_spec.rb
index 719982a1..dae42e66 100644
--- a/spec/overcommit/hook_context/pre_commit_spec.rb
+++ b/spec/overcommit/hook_context/pre_commit_spec.rb
@@ -207,7 +207,7 @@
         end
 
         repo do
-          `git -c protocol.file.allow=always submodule add #{submodule} sub > #{File::NULL} 2>&1`
+          `git submodule add #{submodule} sub > #{File::NULL} 2>&1`
           `git commit -m "Add submodule"`
           echo('Hello World', 'sub/submodule-file')
           `git submodule foreach "git add submodule-file" < #{File::NULL}`
@@ -383,7 +383,7 @@
         end
 
         repo do
-          `git -c protocol.file.allow=always submodule add #{submodule} sub > #{File::NULL} 2>&1`
+          `git submodule add #{submodule} sub > #{File::NULL} 2>&1`
           `git commit -m "Add submodule"`
           echo('Hello World', 'sub/submodule-file')
           `git submodule foreach "git add submodule-file" < #{File::NULL}`
@@ -409,7 +409,7 @@
         end
 
         repo do
-          `git -c protocol.file.allow=always submodule add #{submodule} sub > #{File::NULL} 2>&1`
+          `git submodule add #{submodule} sub > #{File::NULL} 2>&1`
           `git commit -m "Add submodule"`
           echo('Hello World', 'sub/submodule-file')
           `git submodule foreach "git add submodule-file" < #{File::NULL}`
@@ -441,7 +441,7 @@
         end
 
         repo do
-          `git -c protocol.file.allow=always submodule add #{submodule} sub > #{File::NULL} 2>&1`
+          `git submodule add #{submodule} sub > #{File::NULL} 2>&1`
           `git commit -m "Add submodule"`
           `git rm sub`
           example.run
@@ -470,7 +470,7 @@
       end
 
       repo do
-        `git -c protocol.file.allow=always submodule add #{submodule} test-sub 2>&1 > #{File::NULL}`
+        `git submodule add #{submodule} test-sub 2>&1 > #{File::NULL}`
         expect(subject).to_not include File.expand_path('test-sub')
       end
     end
diff --git a/spec/overcommit/hook_context/run_all_spec.rb b/spec/overcommit/hook_context/run_all_spec.rb
index c6696edc..516fb70b 100644
--- a/spec/overcommit/hook_context/run_all_spec.rb
+++ b/spec/overcommit/hook_context/run_all_spec.rb
@@ -46,8 +46,7 @@
         end
 
         repo do
-          git_config = '-c protocol.file.allow=always'
-          `git #{git_config} submodule add #{submodule} test-sub 2>&1 > #{File::NULL}`
+          `git submodule add #{submodule} test-sub 2>&1 > #{File::NULL}`
           example.run
         end
       end
diff --git a/spec/overcommit/installer_spec.rb b/spec/overcommit/installer_spec.rb
index 8739a70e..c7cfb05e 100644
--- a/spec/overcommit/installer_spec.rb
+++ b/spec/overcommit/installer_spec.rb
@@ -231,7 +231,7 @@ def hook_files_installed?(hooks_dir)
       context 'which has an external git dir' do
         let(:submodule) { File.join(target, 'submodule') }
         before do
-          system 'git', '-c', 'protocol.file.allow=always', 'submodule', 'add', target, 'submodule',
+          system 'git', 'submodule', 'add', target, 'submodule',
                  chdir: target, out: :close, err: :close
         end
         let(:submodule_git_file) { File.join(submodule, '.git') }