Changes to allowed git behavior for ASF git repo

[Ian Maxon <im...@uci.edu>]

Hi all,
As of Monday, for ASF repos, force pushes and tag deletions have been
enabled by ASF Infra. It use to be that master wasn't allowed force pushes,
and until this change it had been the case that no force pushes, even for
branches and tags, were allowed.

The only part of the repository that is protected now is refs under rel/ .
Based on this, I think we should probably copy our current release tag and
any new ones to be under this tag to keep them preserved as they should be.

We normally don't push to ASF without the help of a tool at all, but, if
you do have the ASF repo in your remote list from the repository you
normally work on, now is probably a good time to remove it, because now it
is especially dangerous. It only takes one accidental git push -f to make
your day that much more interesting! :) git-asf adds the branch temporarily
for you, so there shouldn't be a need to have it, unless you are doing
things other than pushing changes from Gerrit.

Just a FYI, as I don't know how many of us are subscribed to the
infrastructure lists.

-Ian