phabricator: allow multiple DREVSPEC args to phabread|phabimport|phabupdate...
phabricator: allow multiple DREVSPEC args to phabread|phabimport|phabupdate
Per Augie's request. Like regular revsets, the result is the union of all given
specs. Unlike regular revsets, these don't resolve in parent -> child order,
and should be specified as such on the command line.
This change invalidated a previous test using an empty `hg phabread`, so it has
been switched to `hg debugcallconduit` to preserve that coverage.
Differential Revision:
https://phab.mercurial-scm.org/D8233
