Allow messages to continue being queued during the shutdown period,
right up until the final loop iteration, even though this is racy, as
too many things depend on .defer() during exit right now.
This doesn't hurt the spirit of the check: it still catches the worst
situation where $user accidentally shut down Broker then tried to
continue using it.
* origin/dmw:
issue #459: initial get_stats() implementation
tests: fallout from #447.
core: use ModuleNotFoundError in imporer if it is available; closes#448.
core: throw error on duplicate add_handler(); closes#447.
service: unregister receiver at shutdown; closes#445.
issue #326: update Changelog.
d2eb01f tests: pin idna to last supporting 2.6-compat version.
b90889c tests: pin idna to last supporting 2.6-compat version.
9da6e6a tests: don't call Router.shutdown() twice.
b2b7e7b tests: file_service_test fixes
04755c3 issue #426: tighten up PushFileService types.
8fa3c74 issue #426: RouterMonitor format incorrect for 3->2 forward.
d8b9634 issue #426: PushFileService missing to_text() call.
1e9f344 issue #426: big hack so reset_connection has task_var access
18bfde5 issue #444: update Changelog.
835bead tests: allow running scripts from any subdir.
81c93e1 ci: remove duplicate /usr/bin/time call
ca9ae45 issue #426: TemporaryEnvironment must coerce to Unicode.
4bc0d0e issue #426: apply_mode_spec() must handle bytes.
a8921bb tests: fix scaling in fork_histogram
374a361 docs: try to fix CSS difference between local and rtfd
861be2e docs: wrap text around logos
b084d83 docs: fit SVG viewbox to ansible logo
98d06e2 docs: delete shame.rst to make room for new chapters.
5f3244a docs: import pcaps (using LFS) to regenerate charts.
6936b93 tests: import fork_histogram.py.
5a96d13 issue #426: fix all.yml sorting, one more delegate_to
bd82fa1 issue #426: fix low_level_execute_command.yml breakage.
a6e6bc4 issue #426: to_text filter.
d15f533 Turn on Travis build notifcations, but send them to IRC.
9d87f03 issue #426: disable Ansible smart transport.
49d37bf issue #426: remove LANG and LC_ALL during tests.
a6e6fd1 issue #426: more 2->3 test fixes.
67f710f issue #426: use delegate_to in fixup_perms2 and copy.yml
a67a436 docs: add #374 to Changelog.
2b229a6 docs: add thanks entry.
David Wilson