grep: re-order rev-parsing loop

We loop over the arguments, but every branch of the loop
hits either a "continue" or a "break". Surely we can make
this simpler.

The final conditional is:

  if (arg is a rev) {
	  ... handle rev ...
	  continue;
  }
  break;

We can rewrite this as:

  if (arg is not a rev)
	  break;

  ... handle rev ...

That makes the flow a little bit simpler, and will make
things much easier to follow when we add more logic in
future patches.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/grep.c

@@ -1154,20 +1154,22 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		const char *arg = argv[i];
 		unsigned char sha1[20];
 		struct object_context oc;
+		struct object *object;
+
 		if (!strcmp(arg, "--")) {
 			i++;
 			seen_dashdash = 1;
 			break;
 		}
-		/* Is it a rev? */
-		if (!get_sha1_with_context(arg, 0, sha1, &oc)) {
-			struct object *object = parse_object_or_die(sha1, arg);
+
+		/* Stop at the first non-rev */
+		if (get_sha1_with_context(arg, 0, sha1, &oc))
+			break;
+
+		object = parse_object_or_die(sha1, arg);
 		if (!seen_dashdash)
 			verify_non_filename(prefix, arg);
 		add_object_array_with_path(object, arg, &list, oc.mode, oc.path);
-			continue;
-		}
-		break;
 	}
 
 	/* The rest are paths */