[PATCH 2+3/3] stash: tolerate missing user identity

[Junio C Hamano <gitster@pobox.com>]

The "git stash" command insists on having a usable user identity to
the same degree as the "git commit-tree" and "git commit" commands
do, because it uses the same codepath that creates commit objects
as these commands.

It is not strictly necesary to do so.  Check if we will barf before
creating commit objects and then supply fake identity to please the
machinery that creates commits.

This is not that much of usability improvement, as the users who run
"git stash" would eventually want to record their changes that are
temporarily stored in the stashes in a more permanent history by
committing, and they must do "git config user.{name,email}" at that
point anyway, so arguably this change is only delaying a step that
is necessary to work in the repository.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

 * This time with a proposed commit log message and a flip to the
   test; this would be able to replce 2/3 and 3/3 without waiting
   for ps/stash-in-c to stabilize and become ready to be based on
   further work like this one.

   We need to extend the test so that when a reasonable identity is
   present, the stashes are created under that identity and not with
   the fallback one, which I do not think is tested with the previous
   step, so there still is a bit of room to improve [PATCH 1/3]

 git-stash.sh     | 17 +++++++++++++++++
 t/t3903-stash.sh |  2 +-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/git-stash.sh b/git-stash.sh
index 94793c1a91..789ce2f41d 100755
--- a/git-stash.sh
+++ b/git-stash.sh
@@ -55,6 +55,20 @@ untracked_files () {
 	git ls-files -o $z $excl_opt -- "$@"
 }
 
+prepare_fallback_ident () {
+	if ! git -c user.useconfigonly=yes var GIT_COMMITTER_IDENT >/dev/null 2>&1
+	then
+		GIT_AUTHOR_NAME="git stash"
+		GIT_AUTHOR_EMAIL=git@stash
+		GIT_COMMITTER_NAME="git stash"
+		GIT_COMMITTER_EMAIL=git@stash
+		export GIT_AUTHOR_NAME
+		export GIT_AUTHOR_EMAIL
+		export GIT_COMMITTER_NAME
+		export GIT_COMMITTER_EMAIL
+	fi
+}
+
 clear_stash () {
 	if test $# != 0
 	then
@@ -67,6 +81,9 @@ clear_stash () {
 }
 
 create_stash () {
+
+	prepare_fallback_ident
+
 	stash_msg=
 	untracked=
 	while test $# != 0
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index a9a573efa0..3dcf2f14d1 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -1096,7 +1096,7 @@ test_expect_success 'stash -- <subdir> works with binary files' '
 	test_path_is_file subdir/untracked
 '
 
-test_expect_failure 'stash works when user.name and user.email are not set' '
+test_expect_success 'stash works when user.name and user.email are not set' '
 	git reset &&
 	>1 &&
 	git add 1 &&
-- 
2.19.1-801-gd582ea202b