Re: [RFC PATCH 2/2] push: support pushing to a remote group

Usman Akinyemi [off-list ref] writes:

Also, in the cover letter, I asked some questions. I think you might
have missed it.

Quoting here again:
"
  - push.default = simple interacts poorly with group pushes when the
    current branch has no upstream set, since setup_default_push_refspecs()
    will die on the first remote that is not the upstream. Users should
    use push.default = current or explicit refspecs for group pushes.
    It is worth discussing whether the group push path should automatically
    imply push.default = current, or whether a clear error message
    directing the user to configure this would be sufficient.

  - force-with-lease semantics across a group push are currently
    unmodified — the same CAS constraints are forwarded to every remote
    in the group. Whether this is the right behaviour or whether
    per-remote lease tracking is needed is an open question.
"

I will want feedback on this also.

Quite honestly, I do not have strong opinions on either of these
points, primarily because the answer would become self evident if we
follow a simple general principle to explain this feature to end
users, which is:

When you have N remotes r1, r2, ..., rN, and a remote group G that
expands (possibly recursively) to these N remotes, then for any and
all values of $options and $args, this command invocation

    $ git push $options G $args

should mean exactly the same thing as

    $ git push $options r1 $args
    $ git push $options r2 $args
    ...
    $ git push $options rN $args

So the answer to the first one would be:

    "git push r1" (without any other parameters) may work while "git
    push r2" (the same, wihtout any other parameters) may fail,
    depending on how the push.default is set and on what branch you
    run these two pushes.  "git push G" should behave the same way.
    There is nothing extra fancy needs to be done.  If the user
    wants to push to these N remotes as a whole in an identical way
    by using remote group G, they are the one who is responsible to
    make this sequences of pushes "git push r1; git push r2; ..."
    make sense.

The answer to the second one would be derived the same way.  If
$options includes the "--force-with-lease=<commit>", then the
command should behave as if copies of the command that pushes to
these N remotes, "git push --force-with-lease=<commit> r$i", are
invoked.  If <commit> is not given (which is not a recommended even
for pushes to a single remote, because with background fetching,
guesses based on the remote-tracking branches are never be
reliable), the command may guess what commit to expect on the remote
the same way as if these N independent pushes are made without using
group feature (which of course may make different guesses for each
remote, if their remote-tracking branches are pointing at different
commits).