Merge branch 'tr/protect-low-3-fds'

When "git" is spawned in such a way that any of the low 3 file
descriptors is closed, our first open() may yield file descriptor 2,
and writing error message to it would screw things up in a big way.

* tr/protect-low-3-fds:
  git: ensure 0/1/2 are open in main()
  daemon/shell: refactor redirection of 0/1/2 from /dev/null

daemon.c

@@ -1047,18 +1047,6 @@ static int service_loop(struct socketlist *socklist)
 	}
 }
 
-/* if any standard file descriptor is missing open it to /dev/null */
-static void sanitize_stdfds(void)
-{
-	int fd = open("/dev/null", O_RDWR, 0);
-	while (fd != -1 && fd < 2)
-		fd = dup(fd);
-	if (fd == -1)
-		die_errno("open /dev/null or dup failed");
-	if (fd > 2)
-		close(fd);
-}
-
 #ifdef NO_POSIX_GOODIES
 
 struct credentials;