Merge branch 'cb/maint-orphan-merge-noclobber' into next

* cb/maint-orphan-merge-noclobber:
  do not overwrite untracked during merge from unborn branch

Conflicts:
	t/t7607-merge-overwrite.sh

diff --cc builtin/merge.c
Simple merge

diff --cc t/t7607-merge-overwrite.sh
index e49dd8023cf2b244a0831a80f559a016d786820c,8317a574ce2a56162094e817499fb188043ba8da..d4a499dee2ec3daabdba75eb6185778567204b0b
--- 1/t/t7607-merge-overwrite.sh
--- 2/t/t7607-merge-overwrite.sh
+++ b/t/t7607-merge-overwrite.sh
@@@ -90,41 -84,20 +90,57 @@@ 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
 +'
 +
 +test_expect_success 'will not overwrite untracked file in leading path' '
 +      git reset --hard c0 &&
 +      rm -rf sub &&
 +      cp important sub &&
 +      test_must_fail git merge sub &&
 +      test_path_is_missing .git/MERGE_HEAD &&
 +      test_cmp important sub
 +'
 +
 +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