discovery: avoid dropping remote heads hidden locally An extra post processing was added to recognize remote heads that are hidden locally as "common" instead of "unknown". However, this processing was removing such hidden heads from the remote heads sets. It had no impact because we used to pull phase information from all remote heads. This series will replace the phase pulling operation to a more efficient process but requires the unmodified pulled set information.

test-patchbomb: use mocktime The test was using system time for displaying ETAs, which could be flaky if the sysload is high. This patch extracts mocktime.py from test-progress.t to make sure test-patchbomb.t is unaffected by system time. Differential Revision: https://phab.mercurial-scm.org/D844