Merge branch 'tr/merge-unborn-clobber'

* tr/merge-unborn-clobber:
  Exhibit merge bug that clobbers index&WT

Conflicts:
	t/t7607-merge-overwrite.sh

t/t7607-merge-overwrite.sh

@@ -156,4 +156,20 @@ test_expect_success 'will not overwrite untracked file on unborn branch' '
 	test_cmp important c0.c
 '
 
+test_expect_success 'set up unborn branch and content' '
+	git symbolic-ref HEAD refs/heads/unborn &&
+	rm -f .git/index &&
+	echo foo > tracked-file &&
+	git add tracked-file &&
+	echo bar > untracked-file
+'
+
+test_expect_failure 'will not clobber WT/index when merging into unborn' '
+	git merge master &&
+	grep foo tracked-file &&
+	git show :tracked-file >expect &&
+	grep foo expect &&
+	grep bar untracked-file
+'
+
 test_done