* Rename scripts-dev to have suffices

* Update references to `scripts-dev`

* Changelog

* These scripts don't pass mypy

* Don't use `tox` for `check-sampleconfig`
* Don't use `tox` for check-newsfragment

* Fix AssertionErrors after purging events

If you purged a bunch of events from your database, and then restarted synapse
without receiving more events, then you would get a bunch of AssertionErrors on
restart.

This fixes the situation by rewinding the stream processors.

* `check-newsfragment`: ignore deleted newsfiles

Use $(...) notation instead of legacy backticked `...`.

https://github.com/koalaman/shellcheck/wiki/SC2006



Signed-off-by: Dan Callahan <danc@element.io>

Double quote to prevent globbing and word splitting.

https://github.com/koalaman/shellcheck/wiki/SC2086



Signed-off-by: Dan Callahan <danc@element.io>

Prefer [ p ] && [ q ] as [ p -a q ] is not well defined.

https://github.com/koalaman/shellcheck/wiki/SC2166



Signed-off-by: Dan Callahan <danc@element.io>

use PULL_REQUEST_NUMBER instead of BUILDKITE_PULL_REQUEST
remove the other user of BUILDKITE_PULL_REQUEST, namely merge_base_branch.sh

On NixOS, `bash` isn't under `/bin/bash` but rather in some directory in `$PATH`. Locally, I've been patching those scripts to make them work.

`/usr/bin/env` seems to be the only [portable way](https://unix.stackexchange.com/questions/29608/why-is-it-better-to-use-usr-bin-env-name-instead-of-path-to-name-as-my

) to use binaries from the PATH as interpreters.

Signed-off-by: Quentin Gliech <quentingliech@gmail.com>

This PR:

* Reduces the amount of noise in the `check-newsfragment` CI output by hiding the dependency installation output by default.
* Prints a link to the changelog/debian changelog section of the contributing guide if an error is found.

* Fix check-newsfragment script

I previously broke this so that it always succeeded...

* more fixes

* fix newsfiles

* You need an entry in the debian changelog (and not a regular newsfragment)
  for debian packaging changes.
* Regular newsfragments must end in full stops.