Re: [PATCH] pack-refs: dereference .git/packed-refs if it is a symlink

Peter Baumann [off-list ref] writes:

git-new-workdir creates a new working directory where everything
necessary, including .git/packed-refs, is symlinked to your master repo.
But git-pack-refs breaks the symlink, so you could accidentally loose some
refs.

This fixes git-pack-refs to first dereference .git/packed-refs if it is a
symlink. While we are it, add some tests to prevent this from happening
again.

Because you are only fixing the case where the worktree is
borrowing the packed-refs file from a real repository with a
symlink trick, and we do not know if somebody had his
packed-refs as a symlink to some random place for reasons other
than creating a lightweight worktree (maybe there was a
mistake), I am wondering if it makes sense to be more strict
about the value we read from readlink().

For example, if it does not end with "/packed-refs", doesn't it
suggest that the reason because the symlink is there is
different from the case you are handling (i.e. it is not a
packed-refs symlink in a lightweight worktree that points at the
corresponding real repository)?  I wonder if in such a case we
would want to signal an error, instead of overwriting whatever
real file the symlink points at.  Or is it too strict and
paranoid?  I dunno.