t3903: document a pair of directory/file bugs

There are three tests here, because the second bug is documented with
two tests: a file -> directory change and a directory -> file change.
The reason for the two tests is just to verify that both are indeed
broken but that both will be fixed by the same simple change (which will
be provided in a subsequent patch).

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t3903-stash.sh

@@ -1307,4 +1307,62 @@ test_expect_success 'stash -c stash.useBuiltin=false warning ' '
 	test_must_be_empty err
 '
 
+test_expect_failure 'git stash succeeds despite directory/file change' '
+	test_create_repo directory_file_switch_v1 &&
+	(
+		cd directory_file_switch_v1 &&
+		test_commit init &&
+
+		test_write_lines this file has some words >filler &&
+		git add filler &&
+		git commit -m filler &&
+
+		git rm filler &&
+		mkdir filler &&
+		echo contents >filler/file &&
+		git stash push
+	)
+'
+
+test_expect_failure 'git stash can pop file -> directory saved changes' '
+	test_create_repo directory_file_switch_v2 &&
+	(
+		cd directory_file_switch_v2 &&
+		test_commit init &&
+
+		test_write_lines this file has some words >filler &&
+		git add filler &&
+		git commit -m filler &&
+
+		git rm filler &&
+		mkdir filler &&
+		echo contents >filler/file &&
+		cp filler/file expect &&
+		git stash push --include-untracked &&
+		git stash apply --index &&
+		test_cmp expect filler/file
+	)
+'
+
+test_expect_failure 'git stash can pop directory -> file saved changes' '
+	test_create_repo directory_file_switch_v3 &&
+	(
+		cd directory_file_switch_v3 &&
+		test_commit init &&
+
+		mkdir filler &&
+		test_write_lines some words >filler/file1 &&
+		test_write_lines and stuff >filler/file2 &&
+		git add filler &&
+		git commit -m filler &&
+
+		git rm -rf filler &&
+		echo contents >filler &&
+		cp filler expect &&
+		git stash push --include-untracked &&
+		git stash apply --index &&
+		test_cmp expect filler
+	)
+'
+
 test_done