update-reset.sh: Fix shellcheck style errors

Library/Homebrew/cmd/update-reset.sh

@@ -10,40 +10,40 @@ homebrew-update-reset() {
 
   for option in "$@"
   do
-    case "$option" in
+    case "${option}" in
       -\?|-h|--help|--usage)          brew help update-reset; exit $? ;;
       --debug)                        HOMEBREW_DEBUG=1 ;;
       -*)
-        [[ "$option" = *d* ]] && HOMEBREW_DEBUG=1
+        [[ "${option}" = *d* ]] && HOMEBREW_DEBUG=1
         ;;
       *)
-        REPOS+=("$option")
+        REPOS+=("${option}")
         ;;
     esac
   done
 
-  if [[ -n "$HOMEBREW_DEBUG" ]]
+  if [[ -n "${HOMEBREW_DEBUG}" ]]
   then
     set -x
   fi
 
   if [[ -z "${REPOS[*]}" ]]
   then
-    REPOS+=("$HOMEBREW_REPOSITORY" "$HOMEBREW_LIBRARY"/Taps/*/*)
+    REPOS+=("${HOMEBREW_REPOSITORY}" "${HOMEBREW_LIBRARY}"/Taps/*/*)
   fi
 
   for DIR in "${REPOS[@]}"
   do
-    [[ -d "$DIR/.git" ]] || continue
-    ohai "Fetching $DIR..."
-    git -C "$DIR" fetch --force --tags origin
-    git -C "$DIR" remote set-head origin --auto >/dev/null
+    [[ -d "${DIR}/.git" ]] || continue
+    ohai "Fetching ${DIR}..."
+    git -C "${DIR}" fetch --force --tags origin
+    git -C "${DIR}" remote set-head origin --auto >/dev/null
     echo
 
-    ohai "Resetting $DIR..."
-    head="$(git -C "$DIR" symbolic-ref refs/remotes/origin/HEAD)"
+    ohai "Resetting ${DIR}..."
+    head="$(git -C "${DIR}" symbolic-ref refs/remotes/origin/HEAD)"
     head="${head#refs/remotes/origin/}"
-    git -C "$DIR" checkout --force -B "$head" origin/HEAD
+    git -C "${DIR}" checkout --force -B "${head}" origin/HEAD
     echo
   done
 }