Avoid ambiguous error message if pack.idx header is wrong

Print the index version when an error occurs so the user
knows what type of header (and size) we thought the index
should have had.

Signed-off-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sha1_file.c

@@ -497,7 +497,7 @@ static int check_packed_git_idx(const char *path,  struct packed_git *p)
 		 */
 		if (idx_size != 4*256 + nr * 24 + 20 + 20) {
 			munmap(idx_map, idx_size);
-			return error("wrong index file size in %s", path);
+			return error("wrong index v1 file size in %s", path);
 		}
 	} else if (version == 2) {
 		/*
@@ -519,7 +519,7 @@ static int check_packed_git_idx(const char *path,  struct packed_git *p)
 			max_size += (nr - 1)*8;
 		if (idx_size < min_size || idx_size > max_size) {
 			munmap(idx_map, idx_size);
-			return error("wrong index file size in %s", path);
+			return error("wrong index v2 file size in %s", path);
 		}
 		if (idx_size != min_size) {
 			/* make sure we can deal with large pack offsets */