[PATCH v4 0/2] am: support --empty-commit=(die|skip|asis) option to am empty commits

Since that git has supported the --always option for the git-format-patch command to create a patch with an empty commit message, git-am should support applying and committing with empty patches.

----------------------------------------------------------------------------

Changes since v1:

 1. add a case when not passing the --always option
 2. rename the --always option to --allow-empty

----------------------------------------------------------------------------

Changes since v2:

 1. rename the --allow-empty option to --empty-commit
 2. introduce three different strategies (die|skip|asis) when trying to
    record empty patches as empty commits.

----------------------------------------------------------------------------

Changes since v3:

 1. generate the missed file for test cases
 2. grep -f cannot be used under Mac OS

----------------------------------------------------------------------------

Aleen (2):
  doc: git-format-patch: describe the option --always
  am: support --empty-commit option to handle empty patches

 Documentation/git-am.txt           |  9 ++++
 Documentation/git-format-patch.txt |  6 ++-
 builtin/am.c                       | 48 ++++++++++++++++++--
 t/t4150-am.sh                      | 73 ++++++++++++++++++++++++++++++
 4 files changed, 130 insertions(+), 6 deletions(-)

base-commit: b550198c73edd4cc058832dcf74b41aeec2adba2
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1076%2Faleen42%2Fnext-v4
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1076/aleen42/next-v4
Pull-Request: https://github.com/gitgitgadget/git/pull/1076

Range-diff vs v3:

 1:  9f1b3dd6d0b = 1:  9f1b3dd6d0b doc: git-format-patch: describe the option --always
 2:  ef33ce8c6f9 ! 2:  b7e30c9b7ab am: support --empty-commit option to handle empty patches
     @@ t/t4150-am.sh: test_expect_success setup '
      +	git commit -m "empty commit" --allow-empty &&
      +
      +	git format-patch --stdout empty-commit^ >empty.patch &&
     ++	git format-patch --stdout --cover-letter empty-commit^ >cover-letter.patch &&
      +	git format-patch --always --stdout empty-commit^ >empty-commit.patch &&
      +
       	# reset time
     @@ t/t4150-am.sh: test_expect_success 'apply binary blob in partial clone' '
      +
      +	git am --empty-commit=skip cover-letter.patch >err &&
      +	test_path_is_missing .git/rebase-apply &&
     -+	git rev-parse empty-commit^ >expected &&
     -+	git rev-parse HEAD >actual &&
     -+	test_cmp expected actual
     ++	test_cmp_rev empty-commit^ HEAD
      +'
      +
      +test_expect_success 'record as an empty commit when meeting e-mail message that lacks a patch' '
      +	git am --empty-commit=asis empty-commit.patch &&
      +	test_path_is_missing .git/rebase-apply &&
     -+	git show empty-commit --format="%B" >expected &&
     ++	{
     ++		git show empty-commit --format="%B" &&
     ++		echo "--" &&
     ++		git version | sed -e "s/^git version //" &&
     ++		echo
     ++	} >expected &&
      +	git show HEAD --format="%B" >actual &&
     -+	grep -f actual expected &&
     ++	test_cmp actual expected &&
      +
      +	git am --empty-commit=asis cover-letter.patch &&
      +	test_path_is_missing .git/rebase-apply &&
     -+	git show empty-commit --format="%B" >expected &&
     ++	{
     ++		echo "*** SUBJECT HERE ***" &&
     ++		echo &&
     ++		echo "*** BLURB HERE ***" &&
     ++		echo &&
     ++		echo "A U Thor (1):" &&
     ++		printf "  " &&
     ++		git show empty-commit --format="%B" &&
     ++		echo "--" &&
     ++		git version | sed -e "s/^git version //" &&
     ++		echo
     ++	} >expected &&
      +	git show HEAD --format="%B" >actual &&
     -+	grep -f actual expected
     ++	test_cmp actual expected
      +'
      +
       test_done