[PATCH 3/3] Mark new entries skip-worktree appropriately

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

Sparse checkout updates worktree based on the old and new
skip-worktree status when $GIT_DIR/info/sparse-checkout changes:

old = ce_skip_worktree(ce);           // current skip-worktree
new = will_have_skip_work_tree(ce);   // from $GIT..sparse-checkout
if (old && !new) add_file_back(ce);   // shrink checkout area
if (!old && new) remove_file_out(ce); [1] // enlarge checkout area

New entries after merging will always have skip-worktree unset
(i.e. old = 0). If those files are filtered out by
$GIT_DIR/info/sparse-checkout (i.e. new != 0), then case [1] will
happen. But there is nothing to remove because they're new.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 t/t1011-read-tree-sparse-checkout.sh |    2 +-
 unpack-trees.c                       |    2 ++
 2 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/t/t1011-read-tree-sparse-checkout.sh b/t/t1011-read-tree-sparse-checkout.sh
index 885578a..86a6246 100755
--- a/t/t1011-read-tree-sparse-checkout.sh
+++ b/t/t1011-read-tree-sparse-checkout.sh
@@ -138,7 +138,7 @@ test_expect_success 'read-tree adds to worktree, absent case' '
 	test ! -f sub/added
 '
 
-test_expect_failure 'read-tree adds to worktree, dirty case' '
+test_expect_success 'read-tree adds to worktree, dirty case' '
 	echo init.t > .git/info/sparse-checkout &&
 	git checkout -f removed &&
 	mkdir sub &&
diff --git a/unpack-trees.c b/unpack-trees.c
index 7ea8c5f..f98b1cb 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -1091,6 +1091,8 @@ static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
 	if (!old) {
 		if (verify_absent(merge, "overwritten", o))
 			return -1;
+		if (!o->skip_sparse_checkout && will_have_skip_worktree(merge, o))
+			update |= CE_SKIP_WORKTREE;
 		invalidate_ce_path(merge, o);
 	} else if (!(old->ce_flags & CE_CONFLICTED)) {
 		/*
-- 
1.7.1.rc1.69.g24c2f7