archive: specfile support (--pretty=format: in archive files)
Add support for a new attribute, specfile. Files marked as being
specfiles are expanded by git-archive when they are written to an
archive. It has no effect on worktree files. The same placeholders
as those for the option --pretty=format: of git-log et al. can be
used.
The attribute is useful for creating auto-updating specfiles. It is
limited by the underlying function format_commit_message(), though.
E.g. currently there is no placeholder for git-describe like output,
and expanded specfiles can't contain NUL bytes. That can be fixed
in format_commit_message() later and will then benefit users of
git-log, too.
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>