Turns out you can configure format-patch with `--no-prefix` and some
people (*cough cough* mat) have that in their standard setup, so the
assumption of needing to strip 1 level of prefix does not necessarily
hold.
Also fix a few more issues:
- some people (*cough cough* still mat) also use `-n` by default,
which adds the series sequence (`n/m`) even for a single patch,
handle that correctly
- logging patch application errors is pretty useful when patching
fails and I'm trying to get the information via logs, do that
- especially when I decide to add error messages to tracking *but
forgot to show the chatter by default*, fix that as well
The commit-based patcher worked first try, and patch-based would have
worked too if not for those meddling kids. In the future it might be a
good idea to reify the stripping level (`-p`) on the patch object
though, and maybe provide a computed preview of the list of files to
patch, so issues are easier for the operator to diagnose.
Unstaged changes can be useful or necessary for some tasks
e.g. absolute emergency (where even faking the state of a staging is
not really desirable, if that's even possible anymore), or changes
which are so broad they're difficult to stage (e.g. t10s updates).
Add a new object which serves as a queue for patch to direct-apply,
with support for either text patches (udiff style out of git show or
format-patch) or commits to cherry-pick. In the former case, the part
of the show / format-patch before the diff itself is used for the
commit metadata (author, committer, dates, message) whereas for the
commit version the commit itself is reused as-is.
Applied patches are simply disabled for traceability.
Fixes#926
