Remove deferred execution in _forgit_log

bin/git-forgit

@@ -95,25 +95,30 @@ _forgit_is_file_tracked() {
     git ls-files "$1" --error-unmatch &> /dev/null
 }
 
+_forgit_log_preview() {
+    sha=$1
+    shift
+    echo $sha | xargs -I% git show --color=always -U$_forgit_preview_context % -- "$@" | $_forgit_show_pager
+}
+
 # git commit viewer
 _forgit_log() {
     _forgit_inside_work_tree || return 1
-    local opts graph files log_format preview_cmd enter_cmd
+    local opts graph files log_format enter_cmd
     files=$(sed -nE 's/.*-- (.*)/\1/p' <<< "$*") # extract files parameters for `git show` command
-    preview_cmd="echo {} | $_forgit_extract_sha | xargs -I% git show --color=always -U$_forgit_preview_context % -- $files | $_forgit_show_pager"
-    enter_cmd="echo {} | $_forgit_extract_sha | xargs -I% ${FORGIT} diff %^! $files"
+    enter_cmd="echo {1} | xargs -I% ${FORGIT} diff %^! $files"
     opts="
         $FORGIT_FZF_DEFAULT_OPTS
         +s +m --tiebreak=index
         --bind=\"enter:execute($enter_cmd)\"
         --bind=\"ctrl-y:execute-silent(echo {} | $_forgit_extract_sha | ${FORGIT_COPY_CMD:-pbcopy})\"
-        --preview=\"$preview_cmd\"
+        --preview=\"$FORGIT log_preview {1} $file\"
         $FORGIT_LOG_FZF_OPTS
     "
     graph=--graph
     [[ $FORGIT_LOG_GRAPH_ENABLE == false ]] && graph=
     log_format=${FORGIT_GLO_FORMAT:-$_forgit_log_format}
-    eval "git log $graph --color=always --format='$log_format' $FORGIT_LOG_GIT_OPTS $* $_forgit_emojify" |
+    git log $graph --color=always --format="$log_format" $FORGIT_LOG_GIT_OPTS $* $_forgit_emojify |
         FZF_DEFAULT_OPTS="$opts" fzf
     fzf_exit_code=$?
     # exit successfully on 130 (ctrl-c/esc)
@@ -722,6 +727,7 @@ private_commands=(
     "ignore_preview"
     "revert_preview"
     "yank_sha"
+    "log_preview"
 )
 
 cmd="$1"