Merge branch 'ps/stash-push-pathspec-fix' into maint

"git stash push <pathspec>" did not work from a subdirectory at all.
Bugfix for a topic in v2.13

* ps/stash-push-pathspec-fix:
  git-stash: fix pushing stash with pathspec from subdir

git-stash.sh

@@ -19,6 +19,7 @@ OPTIONS_SPEC=
 START_DIR=$(pwd)
 . git-sh-setup
 require_work_tree
+prefix=$(git rev-parse --show-prefix) || exit 1
 cd_to_toplevel
 
 TMP="$GIT_DIR/.git-stash.$$"
@@ -273,6 +274,8 @@ push_stash () {
 		shift
 	done
 
+	eval "set $(git rev-parse --sq --prefix "$prefix" -- "$@")"
+
 	if test -n "$patch_mode" && test -n "$untracked"
 	then
 		die "$(gettext "Can't use --patch and --include-untracked or --all at the same time")"

t/t3903-stash.sh

@@ -812,6 +812,22 @@ test_expect_success 'stash -- <pathspec> stashes and restores the file' '
 	test_path_is_file bar
 '
 
+test_expect_success 'stash -- <pathspec> stashes in subdirectory' '
+	mkdir sub &&
+	>foo &&
+	>bar &&
+	git add foo bar &&
+	(
+		cd sub &&
+		git stash push -- ../foo
+	) &&
+	test_path_is_file bar &&
+	test_path_is_missing foo &&
+	git stash pop &&
+	test_path_is_file foo &&
+	test_path_is_file bar
+'
+
 test_expect_success 'stash with multiple pathspec arguments' '
 	>foo &&
 	>bar &&