[PATCH v9 0/2] am: support --empty=(die|drop|keep) option to handle empty patches

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.

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Changes since v1:

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

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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.

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Changes since v3:

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

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Changes since v4:

 1. rename the --empty-commit option to --empty.
 2. rename three different strategies (die|skip|asis) to die, drop and keep
    correspondingly.

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Changes since v5:

 1. throw an error when passing --empty option without value.

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Changes since v6:

 1. add i18n resources.

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Changes since v7:

 1. update code according to the seen branch.
 2. fix the wrong document of git-am.
 3. sign off commits by a real name.

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Changes since v8:

 1. update the committer's name with my real name to fix DCO of GGG.

Aleen 徐沛文 (2):
  doc: git-format-patch: describe the option --always
  am: support --empty=<option> to handle empty patches

 Documentation/git-am.txt           |  8 +++++
 Documentation/git-format-patch.txt |  6 +++-
 builtin/am.c                       | 55 +++++++++++++++++++++++++++---
 t/t4150-am.sh                      | 49 ++++++++++++++++++++++++++
 4 files changed, 112 insertions(+), 6 deletions(-)

base-commit: ca35af825273b98fc8dc11527488952f5db8eb80
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1076%2Faleen42%2Fnext-v9
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1076/aleen42/next-v9
Pull-Request: https://github.com/gitgitgadget/git/pull/1076

Range-diff vs v8:

 1:  5d98a088e14 ! 1:  3b41ca3dec7 doc: git-format-patch: describe the option --always
     @@
       ## Metadata ##
     -Author: Aleen <aleen42@vip.qq.com>
     +Author: Aleen 徐沛文 <aleen42@vip.qq.com>
      
       ## Commit message ##
          doc: git-format-patch: describe the option --always
 2:  3ff18e16a7a ! 2:  d2ec18b36af am: support --empty=<option> to handle empty patches
     @@
       ## Metadata ##
     -Author: Aleen <aleen42@vip.qq.com>
     +Author: Aleen 徐沛文 <aleen42@vip.qq.com>
      
       ## Commit message ##
          am: support --empty=<option> to handle empty patches