do not overwrite untracked during merge from unborn branch
In case HEAD does not point to a valid commit yet, merge is
implemented as a hard reset. This will cause untracked files to be
overwritten.
Instead, assume the empty tree for HEAD and do a regular merge. An
untracked file will cause the merge to abort and do nothing. If no
conflicting files are present, the merge will have the same effect
as a hard reset.
Signed-off-by: Clemens Buchacher <drizzd@aon.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t7607-merge-overwrite.sh b/t/t7607-merge-overwrite.sh
index 49f4e15..8317a57 100755
--- a/t/t7607-merge-overwrite.sh
+++ b/t/t7607-merge-overwrite.sh
@@ -84,4 +84,20 @@
test_cmp important c1.c
'
+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
