Phabricator doesn't get notified of new tasks for revision

[abpostelnicu]

It can be seen in D187545 that there were no tasks associated with this revision.
Looking other the logs there was a local mercurial error even if the push was successful on the server side since the tasks for this differential were created, https://treeherder.mozilla.org/jobs?repo=try&revision=9086153f853187d4f43d03b5847042b879d0c6c7

If mercurial is killed libmozevent doesn't capture the exception accordingly in order to also signal Phabricator that something happened. In this case this is a false positive issue since, as mentioned above the pushed was successful on the server.