Re: [PATCH v2] cherry-pick: use trailer instead of free-text for `-x`

"Sean Allred via GitGitGadget" [off-list ref] writes:

From: Sean Allred <redacted>

When recording the origin commit during a cherry-pick, the current label
used is not understood by git-interpret-trailers. Standardize onto the
'normal' trailer format that can be reasonably/reliably parsed and used
by external tooling leveraging git-interpret-trailers.

I am somewhat negative on going in this direction, as we originally
added these "cherry-picked-from" by default, but stopped doing so
for a reason [*1*].  I'd be hesitant to see us spend any engineering
resources on a feature we discourage (not even to deprecate and to
remove).  It is a different story if we change the previous stance
on the "cherry-picked-from" information, though.

I admit I've suggested "Cherry-picked-from:" long time ago [*2*], as
an aside in a discussion, but the discussion was more about treating
the line as a very distinct thing that is different from any other
"trailer" lines.  The last time this was brought up, I thought that
it was deemed unnecessary because interpret-trailer code already
understood by the trailer code [*3*], and we _could_ teach the
interpret-trailer code to rewrite it to "Cherry-picked-from:".  Any
renewed efforts should build on the discussion there, addressing
points raised during the discussion, I think.

Thanks.

[Footnotes and references]

*1* Unlike "revert", "cherry-pick" is done from an unrelated and
    often not even published history, and referring to such a commit
    that the end-user cannot do "git show" does not add much value
    to the history.

*2* https://lore.kernel.org/git/xmqqtwcycqul.fsf@gitster.mtv.corp.google.com/ (local)
*3* https://lore.kernel.org/git/20181106221118.GA9975@sigill.intra.peff.net/ (local)