* use a valid filter in rest/client/v2_alpha test

Signed-off-by: pik <alexander.maznev@gmail.com>

Signed-off-by: pik <alexander.maznev@gmail.com>

 * add invalid filter tests

Signed-off-by: pik <alexander.maznev@gmail.com>

Update README: specify python2.7 in virtualenv

Add a missing yield in device key upload

Fix a couple of logcontext leaks

Use preserve_fn to correctly manage the logcontexts around things we don't want
to yield on.

(this would only very very rarely actually be a useful thing, so the main
problem was the logcontext leak...)

fix up some key verif docstrings

Fix caching of remote servers' signature keys

The `@cached` decorator on `KeyStore._get_server_verify_key` was missing
its `num_args` parameter, which meant that it was returning the wrong key for
any server which had more than one recorded key.

By way of a fix, change the default for `num_args` to be *all* arguments. To
implement that, factor out a common base class for `CacheDescriptor` and `CacheListDescriptor`.

Don't send the full event json over replication

Add some debug to help diagnose weird federation issue

Logcontext docs

Apparently the github RST renderer doesn't like Note blocks.

A few fixes to logcontext things

Avoid resetting state on rejected events

README.md: fix link to client list on matrix.org/docs

Fix a bug in ``logcontext.preserve_fn`` which made it leak context into the
reactor, and add a test for it.

Also, get rid of ``logcontext.reset_context_after_deferred``, which tried to do
the same thing but had its own, different, set of bugs.

This fixes a class of 'Unexpected logcontext' messages, which were happening
because the logcontext was somewhat arbitrarily swapping between the sentinel
and the `run` logcontext.

background_updates was using `call_later` in a way that leaked the logcontext
into the reactor.

We could have rewritten it to do it properly, but given that we weren't using
the fancier facilities provided by `call_later`, we might as well just use
`async.sleep`, which does the logcontext stuff properly.

When we get a rejected event, give it the same state_group as its prev_event,
rather than no state_group at all.

This should fix https://github.com/matrix-org/synapse/issues/1935.

A few non-functional changes:

* A bunch of docstrings to document types
* Split `EventsStore._persist_events_txn` up a bit. Hopefully it's a bit more
  readable.
* Rephrase `EventFederationStore._update_min_depth_for_room_txn` to avoid
  mind-bending conditional.
* Rephrase rejected/outlier conditional in `_update_outliers_txn` to avoid
  mind-bending conditional.

Queue up federation PDUs while a room join is in progress

Signed-off-by: Keyvan Fatehi <keyvanfatehi@gmail.com>

Implement no op for room stream in sync