Fix up default abbrev in setup_revisions() argument parser.

The default abbreviation precision should be DEFAULT_ABBREV as before.

Signed-off-by: Junio C Hamano <junkio@cox.net>

git.c

@@ -286,6 +286,7 @@ static int cmd_log(int argc, const char **argv, char **envp)
 	const char *commit_prefix = "commit ";
 	int shown = 0;
 
+	rev.abbrev = DEFAULT_ABBREV;
 	argc = setup_revisions(argc, argv, &rev, "HEAD");
 	if (argc > 1)
 		die("unrecognized argument: %s", argv[1]);