fix shell syntax error in template

An if clause must not be empty; add a "colon" command.

Signed-off-by: Thorsten Glaser <t.glaser@tarent.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/templates/hooks--pre-push.sample b/templates/hooks--pre-push.sample
index 15ab6d8..1f3bceb 100755
--- a/templates/hooks--pre-push.sample
+++ b/templates/hooks--pre-push.sample
@@ -30,6 +30,7 @@
 	if [ "$local_sha" = $z40 ]
 	then
 		# Handle delete
+		:
 	else
 		if [ "$remote_sha" = $z40 ]
 		then