phabricator: introduce a `phabricator.retry` option For the past 2 days, my connection to phab.mercurial-scm.org became extremely poor. In practice this mean that any conduit call has a fairly high change to hang and die. Giving the amount of call done by the phabricator extension, it means the when I am lucky I can get 1 or 2 Diff to update after a few try, but anything sizeable doesn't have any hope to get through. This changesets introduce a new option for the fabricator extension to try retry failed command itself. So that I can get Diff through. As you can guess, this changeset managed to reach Phabricator thanks to itself. Differential Revision: https://phab.mercurial-scm.org/D9449