-[ -h "$GIT_DIR/HEAD" ] &&
-[ -d "$GIT_DIR/refs" ] &&
-[ -d "$GIT_OBJECT_DIRECTORY/00" ]
+if [ -z "$LONG_USAGE" ]
+then
+ LONG_USAGE="Usage: $0 $USAGE"
+else
+ LONG_USAGE="Usage: $0 $USAGE
+
+$LONG_USAGE"
+fi
+
+case "$1" in
+ -h|--h|--he|--hel|--help)
+ echo "$LONG_USAGE"
+ exit
+esac
+
+if [ -z "$SUBDIRECTORY_OK" ]
+then
+ : ${GIT_DIR=.git}
+ : ${GIT_OBJECT_DIRECTORY="$GIT_DIR/objects"}
+
+ # Make sure we are in a valid repository of a vintage we understand.
+ GIT_DIR="$GIT_DIR" git repo-config --get core.nosuch >/dev/null
+ if test $? = 128
+ then
+ exit
+ fi
+else
+ GIT_DIR=$(git-rev-parse --git-dir) || exit
+fi