Merge branch 'cb/leading-path-removal'

* cb/leading-path-removal:
  use persistent memory for rejected paths
  do not overwrite files in leading path
  lstat_cache: optionally return match_len
  add function check_ok_to_remove()
  t7607: add leading-path tests
  t7607: use test-lib functions and check MERGE_HEAD

Conflicts:
	t/t7607-merge-overwrite.sh

diff --cc cache.h
Simple merge

diff --cc t/t7607-merge-overwrite.sh
index 3988900fc33f0f5f9cdd416096df619aec2d577e,9137866e1a7d0dfed7dd55f089a0c3ecd420237c..4d5ce4e682c1ea69034c3f7789a8ac0c89b12466
--- 1/t/t7607-merge-overwrite.sh
--- 2/t/t7607-merge-overwrite.sh
+++ b/t/t7607-merge-overwrite.sh
@@@ -84,20 -92,52 +92,68 @@@ test_expect_success 'will not overwrit
        test_cmp important c1.c
  '
  
+ test_expect_success 'will not overwrite untracked subtree' '
+       git reset --hard c0 &&
+       rm -rf sub &&
+       mkdir -p sub/f &&
+       cp important sub/f/important &&
+       test_must_fail git merge sub &&
+       test_path_is_missing .git/MERGE_HEAD &&
+       test_cmp important sub/f/important
+ '
+ 
+ cat >expect <<\EOF
+ error: The following untracked working tree files would be overwritten by merge:
+       sub
+       sub2
+ Please move or remove them before you can merge.
+ EOF
+ 
+ test_expect_success 'will not overwrite untracked file in leading path' '
+       git reset --hard c0 &&
+       rm -rf sub &&
+       cp important sub &&
+       cp important sub2 &&
+       test_must_fail git merge sub 2>out &&
+       test_cmp out expect &&
+       test_path_is_missing .git/MERGE_HEAD &&
+       test_cmp important sub &&
+       test_cmp important sub2 &&
+       rm -f sub sub2
+ '
+ 
+ test_expect_failure SYMLINKS 'will not overwrite untracked symlink in leading path' '
+       git reset --hard c0 &&
+       rm -rf sub &&
+       mkdir sub2 &&
+       ln -s sub2 sub &&
+       test_must_fail git merge sub &&
+       test_path_is_missing .git/MERGE_HEAD
+ '
+ 
+ test_expect_success SYMLINKS 'will not be confused by symlink in leading path' '
+       git reset --hard c0 &&
+       rm -rf sub &&
+       ln -s sub2 sub &&
+       git add sub &&
+       git commit -m ln &&
+       git checkout sub
+ '
+ 
 +cat >expect <<\EOF
 +error: Untracked working tree file 'c0.c' would be overwritten by merge.
 +fatal: read-tree failed
 +EOF
 +
 +test_expect_success 'will not overwrite untracked file on unborn branch' '
 +      git reset --hard c0 &&
 +      git rm -fr . &&
 +      git checkout --orphan new &&
 +      cp important c0.c &&
 +      test_must_fail git merge c0 2>out &&
 +      test_cmp out expect &&
 +      test_path_is_missing .git/MERGE_HEAD &&
 +      test_cmp important c0.c
 +'
 +
  test_done