create reflog for reflog-less ref

[Chris Jerdonek <chris.jerdonek@gmail.com>]

Hi,

I wanted to ask on this list if there are any supported ways to create
a reflog for an existing ref that doesn't already have a reflog.

This is more likely to come up for refs not in the standard set (i.e.
HEAD, branches and remote-tracking branches), since reflogs aren't
created by default for those refs.

The only workaround I could think of is using git-update-ref to delete
the ref, and then immediately recreate it using the `--create-reflog`
option (if that option is needed), e.g.:

$ git update-ref -d refs/foo/bar
$ git update-ref -m "my message" --create-reflog refs/foo/bar <SHA>

This seems hacky though because it forces you to pass through a state
where the ref no longer exists. It also requires you to get the ref's
SHA first.

This Stack Overflow reply from 2016 suggests the idea of using `git
update-ref -m MSG REF REF` to add lines to an existing reflog:
https://stackoverflow.com/questions/36770141/can-i-add-a-line-to-the-reflog/36778898#36778898
But it doesn't seem to work to create a reflog (and only seemed to
work for me in limited circumstances otherwise, like adding to HEAD's
reflog). (I tried with version 2.25.0.)

Any thoughts?

Thanks,
--Chris