fix(git-commit)!: allow alias update

BREAKING CHANGE: Prior to this commit, git aliases were not being
updated after every update of oh-my-zsh. In case you were using
git-commit plugin before this commit, please remove your git aliases to
proceed.

plugins/git-commit/git-commit.plugin.zsh

@@ -1,3 +1,8 @@
+if git config --global --get-all alias.$_alias >/dev/null 2>&1 \
+  && ! git config --global --get-all oh-my-zsh.git-commit-alias >/dev/null 2>&1; then
+  return
+fi
+
 local -a _git_commit_aliases
 _git_commit_aliases=(
   'build'
@@ -14,19 +19,18 @@ _git_commit_aliases=(
   'wip'
 )
 
-local alias type
-for type in "${_git_commit_aliases[@]}"; do
+local _alias _type
+for _type in "${_git_commit_aliases[@]}"; do
   # an alias can't be named "revert" because the git command takes precedence
   # https://stackoverflow.com/a/3538791
-  case "$type" in
-  revert) alias=rev ;;
-  *) alias=$type ;;
+  case "$_type" in
+    revert) _alias=rev ;;
+    *) _alias=$_type ;;
   esac
 
-  local func='!a() { if [ "$1" = "-s" ] || [ "$1" = "--scope" ]; then local scope="$2"; shift 2; git commit -m "'$type'(${scope}): ${@}"; else git commit -m "'$type': ${@}"; fi }; a'
-  if ! git config --global --get-all alias.${alias} >/dev/null 2>&1; then
-    git config --global alias.${alias} "$func"
-  fi
+  local _func='!a() { if [ "$1" = "-s" ] || [ "$1" = "--scope" ]; then local scope="$2"; shift 2; git commit -m "'$type'(${scope}): ${@}"; else git commit -m "'$type': ${@}"; fi }; a'
+
+  git config --global alias.$_alias "$_func"
 done
 
-unset _git_commit_aliases alias type func
+git config --global oh-my-zsh.git-commit-alias "true"