Merge branch 'develop' of github.com:matrix-org/synapse into hawkowl/benchmark-lrucache

* 'develop' of github.com:matrix-org/synapse: (484 commits)
  Convert http.HTTPStatus objects to their int equivalent (#7188)
  Reduce the number of calls to `resource.getrusage` (#7183)
  Remove some `run_in_background` calls in replication code (#7203)
  Revert "Revert "Merge pull request #7153 from matrix-org/babolivier/sso_whitelist_login_fallback""
  Revert "Revert "Improve the UX of the login fallback when using SSO (#7152)""
  Revert "Merge pull request #7153 from matrix-org/babolivier/sso_whitelist_login_fallback"
  Revert "Improve the UX of the login fallback when using SSO (#7152)"
  tweak changelog
  1.12.3
  Update docstring per review comments
  Fix device list update stream ids going backward (#7158)
  Fix the debian build in a better way. (#7212)
  Fix changelog wording
  1.12.2
  Pin Pillow>=4.3.0,<7.1.0 to fix dep issue
  1.12.1
  review comment
  1.12.1
  Support SAML in the user interactive authentication workflow. (#7102)
  Allow admins to create aliases when they are not in the room (#7191)
  ...

Author: anoadragon453

.buildkite/docker-compose.py35.pg95.yaml

@@ -0,0 +1,13 @@
+#!/bin/bash
+
+# this script is run by buildkite in a plain `xenial` container; it installs the
+# minimal requirements for tox and hands over to the py35-old tox environment.
+
+set -ex
+
+apt-get update
+apt-get install -y python3.5 python3.5-dev python3-pip libxml2-dev libxslt-dev zlib1g-dev tox
+
+export LANG="C.UTF-8"
+
+exec tox -e py35-old,combine

.buildkite/docker-compose.py37.pg11.yaml

@@ -39,3 +39,5 @@ Server correctly handles incoming m.device_list_update
 
 # this fails reliably with a torture level of 100 due to https://github.com/matrix-org/synapse/issues/6536
 Outbound federation requests missing prev_events and then asks for /state_ids and resolves the state
+
+Can get rooms/{roomId}/members at a given point

.buildkite/docker-compose.py37.pg95.yaml

@@ -60,7 +60,7 @@ python 3.6 and to install each tool:
 
 ```
 # Install the dependencies
-pip install -U black flake8 isort
+pip install -U black flake8 flake8-comprehensions isort
 
 # Run the linter script
 ./scripts-dev/lint.sh
@@ -200,6 +200,20 @@ Git allows you to add this signoff automatically when using the `-s`
 flag to `git commit`, which uses the name and email set in your
 `user.name` and `user.email` git configs.
 
+## Merge Strategy
+
+We use the commit history of develop/master extensively to identify
+when regressions were introduced and what changes have been made.
+
+We aim to have a clean merge history, which means we normally squash-merge
+changes into develop. For small changes this means there is no need to rebase
+to clean up your PR before merging. Larger changes with an organised set of
+commits may be merged as-is, if the history is judged to be useful.
+
+This use of squash-merging will mean PRs built on each other will be hard to 
+merge. We suggest avoiding these where possible, and if required, ensuring
+each PR has a tidy set of commits to ease merging.
+
 ## Conclusion
 
 That's it! Matrix is a very open and collaborative project as you might expect