Change stable version switching to respect active

This previously used the `machine` tag that was turned off when a user de-activated the version,
but never turned back on when they re-activated it.

This changes to just use the `active` flag on the Version,
so we will update the stable version if the existing one is `active`,
and not if it isn't,
which makes _way_ more sense.

Author: ericholscher

readthedocs/projects/models.py

@@ -707,7 +707,7 @@ def update_stable_version(self):
             if current_stable:
                 identifier_updated = (
                     new_stable.identifier != current_stable.identifier)
-                if identifier_updated and current_stable.machine:
+                if identifier_updated and current_stable.active:
                     log.info(
                         "Update stable version: {project}:{version}".format(
                             project=self.slug,

readthedocs/projects/views/private.py

@@ -176,7 +176,6 @@ def project_version_detail(request, project_slug, version_slug):
                 log.info('Removing files for version %s', version.slug)
                 broadcast(type='app', task=tasks.clear_artifacts, args=[version.pk])
                 version.built = False
-                version.machine = False
                 version.save()
         url = reverse('project_version_list', args=[project.slug])
         return HttpResponseRedirect(url)