rollback lock files on more signals than just SIGINT

Other signals are also common, for example SIGTERM and SIGHUP.
This patch modifies the lock file mechanism to catch more signals.
It also modifies http-push.c which was missing SIGTERM.

Signed-off-by: Paolo Bonzini <bonzini@gnu.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

http-push.c

@@ -2277,6 +2277,7 @@ int main(int argc, char **argv)
 	signal(SIGINT, remove_locks_on_signal);
 	signal(SIGHUP, remove_locks_on_signal);
 	signal(SIGQUIT, remove_locks_on_signal);
+	signal(SIGTERM, remove_locks_on_signal);
 
 	/* Check whether the remote has server info files */
 	remote->can_update_info_refs = 0;

lockfile.c

@@ -135,6 +135,9 @@ static int lock_file(struct lock_file *lk, const char *path)
 	if (0 <= lk->fd) {
 		if (!lock_file_list) {
 			signal(SIGINT, remove_lock_file_on_signal);
+			signal(SIGHUP, remove_lock_file_on_signal);
+			signal(SIGTERM, remove_lock_file_on_signal);
+			signal(SIGQUIT, remove_lock_file_on_signal);
 			atexit(remove_lock_file);
 		}
 		lk->owner = getpid();

t/t7502-commit.sh

@@ -212,4 +212,18 @@ test_expect_success 'do not fire editor in the presence of conflicts' '
 	test "`cat .git/result`" = "editor not started"
 '
 
+pwd=`pwd`
+cat > .git/FAKE_EDITOR << EOF
+#! /bin/sh
+# kill -TERM command added below.
+EOF
+
+test_expect_success 'a SIGTERM should break locks' '
+	echo >>negative &&
+	sh -c '\''
+	  echo kill -TERM $$ >> .git/FAKE_EDITOR
+	  GIT_EDITOR=.git/FAKE_EDITOR exec git commit -a'\'' && exit 1  # should fail
+	! test -f .git/index.lock
+'
+
 test_done