post-receive-email example hook: fastforward should have been fast_forward

Signed-off-by: Andy Parkins <andyparkins@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

contrib/hooks/post-receive-email

@@ -302,7 +302,7 @@ generate_update_branch_email()
 	# List all of the revisions that were removed by this update, in a fast forward
 	# update, this list will be empty, because rev-list O ^N is empty.  For a non
 	# fast forward, O ^N is the list of removed revisions
-	fastforward=""
+	fast_forward=""
 	rev=""
 	for rev in $(git rev-list $newrev..$oldrev)
 	do