- revert switch to singlespec. This is an insane complexification
for no gain: git-review is a pure cli tool, not a module
to import, and we never had a working python2- version anyway
because all the tooling was excluded from packaging. So
don't create packages that are unusable and deprecated.

- update to 1.28.0 (bsc#1134089):
* Support for auto-configuration of topic names based on the
presence of keywords in the commit message is removed. Previously,
keywords such as bug, bp or lp followed by a number would result
in branch names containing the associated number, e.g. bug/123.
This feature was OpenStack specific, was a frequent source of bugs
and clearly wasn’t being used that often, given that StoryBoard
is a thing now and no one had updated this feature to handle that metadata.
* Fixed usepushurl to work when a read-only mirror being used as origin does not contain refs/changes from gerrit.