contrib/ChangeLog:

	* gcc-changelog/git_commit.py: Print 'Backported from master'
	heading to backported commits.
	* gcc-changelog/test_email.py: Test it.
	* gcc-changelog/test_patches.txt: Add new patch.
	* gcc-changelog/git_repository.py: Add commit_to_date hook.
	* gcc-changelog/git_email.py: Add fuzzy implementation
	of commit_to_date_hook.