heptapod-ci: automatically refresh existing phabricator Diff on push If a changeset have been submitted to Phabricator and a new version is pushed to heptapod, we should refresh the state on Phabricator. If we do not do this, they are a risk of an older version being applied from Phabricator. In this situation content-divergence will be (rightfully) detected by evolution. We only refresh the Diff if the test pass, to avoid updating Phabricator with broken content. Differential Revision: https://phab.mercurial-scm.org/D9451