remove blank filename in error message

When write_loose_object() finds that it is unable to
create a temporary file, it complains, for instance:

    unable to create temporary sha1 filename : Too many open files

That extra space was supposed to be the name of the file,
and will be an empty string if the git_mkstemps_mode() fails.

The name of the temporary file is unimportant; delete it.

Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sha1_file.c

@@ -2511,7 +2511,7 @@ static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
 		if (errno == EACCES)
 			return error("insufficient permission for adding an object to repository database %s", get_object_directory());
 		else
-			return error("unable to create temporary sha1 filename %s: %s", tmp_file, strerror(errno));
+			return error("unable to create temporary file: %s", strerror(errno));
 	}
 
 	/* Set it up */