mergetools / p4mergeon commit log --grep: use the same helper to set -E/-F options as "git grep" (34a4ae5)
   1diff_cmd () {
   2        "$merge_tool_path" "$LOCAL" "$REMOTE"
   3}
   4
   5merge_cmd () {
   6        touch "$BACKUP"
   7        $base_present || >"$BASE"
   8        "$merge_tool_path" "$BASE" "$LOCAL" "$REMOTE" "$MERGED"
   9        check_unchanged
  10}