Since we're about to look up the events themselves anyway, we can skip the
extra db queries here.

When we get a federation request which refers to an event id, make sure that
said event is in the room the caller claims it is in.

(patch supplied by @turt2live)

(mostly just clarifications)

This reverts commit 21d3b879.

Disable logcontext warning

Temporary workaround to #3518 while we release 0.33.0.

Fix visibility of events from erased users over federation

Refactor and optimze filter_events_for_server

Fix perf regression in PR #3530

The get_entities_changed function was changed to return all changed
entities since the given stream position, rather than only those changed
from a given list of entities. This resulted in the function incorrectly
returning large numbers of entities that, for example, caused large
increases in database usage.

Don't return unknown entities in get_entities_changed

check isort by travis

for easier unit testing.

Use parse and asserts from http.servlet