tests/test-xdg.t

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

#if no-windows no-osx

  $ mkdir -p xdgconf/hg
  $ echo '[ui]' > xdgconf/hg/hgrc
  $ echo 'username = foobar' >> xdgconf/hg/hgrc
  $ XDG_CONFIG_HOME="`pwd`/xdgconf" ; export XDG_CONFIG_HOME
  $ unset HGRCPATH
  $ hg config ui.username 2>/dev/null
  foobar

#endif