git-fetch: allow updating the current branch in a bare repository.

Sometimes, people have only fetch access into a bare repository
that is used as a back-up location (or a distribution point) but
does not have a push access for networking reasons, e.g. one end
being behind a firewall, and updating the "current branch" in
such a case is perfectly fine.

This allows such a fetch without --update-head-ok, which is a
flag that should never be used by end users otherwise.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

git-fetch.sh

@@ -231,11 +231,12 @@ update_local_ref () {
     esac
 }
 
-case "$update_head_ok" in
-'')
+# updating the current HEAD with git-fetch in a bare
+# repository is always fine.
+if test -z "$update_head_ok" && test $(is_bare_repository) = false
+then
 	orig_head=$(git-rev-parse --verify HEAD 2>/dev/null)
-	;;
-esac
+fi
 
 # If --tags (and later --heads or --all) is specified, then we are
 # not talking about defaults stored in Pull: line of remotes or

git-sh-setup.sh

@@ -28,6 +28,14 @@ set_reflog_action() {
 	fi
 }
 
+is_bare_repository () {
+	git-repo-config --bool --get core.bare ||
+	case "$GIT_DIR" in
+	.git | */.git) echo false ;;
+	*) echo true ;;
+	esac
+}
+
 if [ -z "$LONG_USAGE" ]
 then
 	LONG_USAGE="Usage: $0 $USAGE"