write_loose_object: don't bother trying to read an old object

Before even calling this, all callers have done a "has_sha1_file(sha1)"
or "has_loose_object(sha1)" check, so there is no point in doing a
second check.

If something races with us on object creation, we handle that in the
final link() that moves it to the right place.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sha1_file.c

@@ -2145,20 +2145,6 @@ static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
 	static char tmpfile[PATH_MAX];
 
 	filename = sha1_file_name(sha1);
-	fd = open(filename, O_RDONLY);
-	if (fd >= 0) {
-		/*
-		 * FIXME!!! We might do collision checking here, but we'd
-		 * need to uncompress the old file and check it. Later.
-		 */
-		close(fd);
-		return 0;
-	}
-
-	if (errno != ENOENT) {
-		return error("sha1 file %s: %s\n", filename, strerror(errno));
-	}
-
 	fd = create_tmpfile(tmpfile, sizeof(tmpfile), filename);
 	if (fd < 0) {
 		if (errno == EPERM)