Merge branch 'maint'

* maint:
  tutorial: gentler illustration of Alice/Bob workflow using gitk
  pretty=format: respect date format options
  make git-shell paranoid about closed stdin/stdout/stderr
  Document gitk --argscmd flag.
  Fix '--dirstat' with cross-directory renaming
  for-each-ref: Allow a trailing slash in the patterns

shell.c

@@ -48,6 +48,19 @@ int main(int argc, char **argv)
 {
 	char *prog;
 	struct commands *cmd;
+	int devnull_fd;
+
+	/*
+	 * Always open file descriptors 0/1/2 to avoid clobbering files
+	 * in die().  It also avoids not messing up when the pipes are
+	 * dup'ed onto stdin/stdout/stderr in the child processes we spawn.
+	 */
+	devnull_fd = open("/dev/null", O_RDWR);
+	while (devnull_fd >= 0 && devnull_fd <= 2)
+		devnull_fd = dup(devnull_fd);
+	if (devnull_fd == -1)
+		die("opening /dev/null failed (%s)", strerror(errno));
+	close (devnull_fd);
 
 	/*
 	 * Special hack to pretend to be a CVS server