phabricator: allow specifying reviewers on phabsend
Sometimes people want to specify reviewer explicitly for a stack. The
webpage only allows changing reviewer for one revision at a time. This patch
adds a `--reviewer` flag to make it easier to specify reviewers.
Test Plan:
On a test Phabricator instance, enable `differential.allow-self-accept`,
assign myself as a reviewer and make sure it works. Also try an invalid
username and make sure it raises.
Differential Revision: https://phab.mercurial-scm.org/D38
$ hg init
$ echo a > a
$ hg ci -Am t
adding a
$ hg mv a b
$ hg ci -Am t1
$ hg debugrename b
b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3
$ hg mv b a
$ hg ci -Am t2
$ hg debugrename a
a renamed from b:37d9b5d994eab34eda9c16b195ace52c7b129980
$ hg debugrename --rev 1 b
b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3