Improve strip behavior of release notes to fix bug

Fix a bug where the formatting of certain Markdown release notes were
inadvertently altered due to stripping indentation off the first line of the
text.

CHANGELOG.md

@@ -7,6 +7,9 @@ chandler is in a pre-1.0 state. This means that its APIs and behavior are subjec
 ## [Unreleased][]
 
 * Your contribution here!
+* Fix a bug where the formatting of certain Markdown release notes were
+  inadvertently altered due to stripping indentation off the first line of the
+  text.
 
 ## [0.3.0][] (2016-03-22)
 

lib/chandler/commands/push.rb

@@ -57,11 +57,19 @@ def exit_with_warning
 
       def changelog_version_and_notes_for_tag(tag)
         version = tag_mapper.call(tag)
-        [version, changelog.fetch(version).strip]
+        notes = strip_surrounding_empty_lines(changelog.fetch(version))
+        [version, notes]
       rescue Chandler::Changelog::NoMatchingVersion
         info("Skip #{tag} (no #{version} entry in #{changelog.basename})".gray)
         nil
       end
+
+      # Returns a new string with leading and trailing empty lines removed. A
+      # line is empty if it is zero-length or contains only whitespace.
+      def strip_surrounding_empty_lines(str)
+        str.sub(/\A[[:space:]]*^/, "")
+           .sub(/$[[:space:]]*\z/, "")
+      end
     end
   end
 end

test/chandler/commands/push_test.rb

@@ -52,6 +52,19 @@ def test_tag_prefix_is_removed_from_title_when_pushing_to_github
     push.call
   end
 
+  def test_leading_and_trailing_blank_lines_are_stripped_when_pushing_to_github
+    @config.changelog
+           .expects(:fetch).with("v1")
+           .returns("\n\n  * one\n\n  * two\n\n")
+    @github.unstub(:create_or_update_release)
+    @github
+      .expects(:create_or_update_release)
+      .with(:tag => "v1", :title => "1", :description => "  * one\n\n  * two")
+
+    push = Chandler::Commands::Push.new(:tags => %w(v1), :config => @config)
+    push.call
+  end
+
   def test_progress_is_pretty_printed_to_stdout
     push = Chandler::Commands::Push.new(
       :tags => %w(v1 v2.0.2 v99.1.18),