Commit hashes should be reproducible.

[zrhoffman]

What I did: Ran tsb prebuild against the same patches.yml twice

Expected result: Same commit hashes each time

Actual result: Different commit hashes each time

More info:

Given a repos.yml and patches.yml file, tsb prebuild should produce the same commit hashes each time for the cherry-picked commits. See other projects like https://github.com/glandium/git-cinnabar, which go to great lengths to produce the same commit hashes each time.

[zrhoffman]

The source of different commit hashes every time is the git committer date changing every time the git cherry-pick command is run. But if the committer date is set to the original changeset's author date, the cherry-picked commit will have the same commit hash each time. This would be run after the git cherry-pick command:

export GIT_COMMITTER_DATE-"$(git log --max-count=1 --pretty=%ad --date=raw $changeset)"
git commit --amend --no-edit

For consistency, the cherry-picked commit could have the author's name and email, too:

export GIT_COMMITTER_NAME="$(git log --max-count=1 --pretty=%an $changeset)"
export GIT_COMMITTER_EMAIL="$(git log --max-count=1 --pretty=%ae $changeset)"