[PATCH 3/6] Stop producing index version 2

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

read-cache.c learned to produce version 2 or 3 depending on whether
extended cache entries exist in 06aaaa0 (Extend index to save more flags
- 2008-10-01), first released in 1.6.1. The purpose is to keep
compatibility with older git. It's been more than three years since
then and git has reached 1.7.9. Drop support for older git.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 read-cache.c                          |    8 +++-----
 t/t2104-update-index-skip-worktree.sh |   12 ------------
 2 files changed, 3 insertions(+), 17 deletions(-)

diff --git a/read-cache.c b/read-cache.c
index e9a20b6..fe6b0e0 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1532,26 +1532,24 @@ int write_index(struct index_state *istate, int newfd)
 {
 	struct sha1file *f;
 	struct cache_header hdr;
-	int i, err, removed, extended;
+	int i, err, removed;
 	struct cache_entry **cache = istate->cache;
 	int entries = istate->cache_nr;
 	struct stat st;
 
-	for (i = removed = extended = 0; i < entries; i++) {
+	for (i = removed = 0; i < entries; i++) {
 		if (cache[i]->ce_flags & CE_REMOVE)
 			removed++;
 
 		/* reduce extended entries if possible */
 		cache[i]->ce_flags &= ~CE_EXTENDED;
 		if (cache[i]->ce_flags & CE_EXTENDED_FLAGS) {
-			extended++;
 			cache[i]->ce_flags |= CE_EXTENDED;
 		}
 	}
 
 	hdr.hdr_signature = htonl(CACHE_SIGNATURE);
-	/* for extended format, increase version so older git won't try to read it */
-	hdr.hdr_version = htonl(extended ? 3 : 2);
+	hdr.hdr_version = htonl(3);
 	hdr.hdr_entries = htonl(entries - removed);
 
 	f = sha1fd(newfd, NULL);
diff --git a/t/t2104-update-index-skip-worktree.sh b/t/t2104-update-index-skip-worktree.sh
index 1d0879b..8221ffa 100755
--- a/t/t2104-update-index-skip-worktree.sh
+++ b/t/t2104-update-index-skip-worktree.sh
@@ -28,19 +28,11 @@ test_expect_success 'setup' '
 	git ls-files -t | test_cmp expect.full -
 '
 
-test_expect_success 'index is at version 2' '
-	test "$(test-index-version < .git/index)" = 2
-'
-
 test_expect_success 'update-index --skip-worktree' '
 	git update-index --skip-worktree 1 sub/1 &&
 	git ls-files -t | test_cmp expect.skip -
 '
 
-test_expect_success 'index is at version 3 after having some skip-worktree entries' '
-	test "$(test-index-version < .git/index)" = 3
-'
-
 test_expect_success 'ls-files -t' '
 	git ls-files -t | test_cmp expect.skip -
 '
@@ -50,8 +42,4 @@ test_expect_success 'update-index --no-skip-worktree' '
 	git ls-files -t | test_cmp expect.full -
 '
 
-test_expect_success 'index version is back to 2 when there is no skip-worktree entry' '
-	test "$(test-index-version < .git/index)" = 2
-'
-
 test_done
-- 
1.7.8.36.g69ee2