mercurial/templates/rss/branches.tmpl

errors: make InterventionRequired subclass Abort

The docstring for `Abort` says that it's for errors raised by commands
and `InterventionRequired` is definitely something raised by commands,
so it seems that it should be an `Abort`. This patch makes it so. It
adds a `coarse_exit_code` (in addition to the already existing
`detailed_exit_code`) to `Abort` to achieve that, since
`InterventionRequired` should result in a special exit code even when
the `ui.detailed-exit-code` config is not set.

Differential Revision: https://phab.mercurial-scm.org/D10737

{header}
    <title>{repo|escape}: branches</title>
    <description>{repo|escape} branch history</description>
    {entries%branchentry}
  </channel>
</rss>