Closes #4516

Devpi preprends a `+` before simple indices. This commit adds support
for them.

Closes #4507

This reverts commit b5c9dc8e.

Adds a sanitize function to host-rules that redacts tokens and passwords from issues and PRs.

Closes #4444

Closes #4346

Too unreliable when tests are executed in parallel

A follow-up to #4246 which was insufficient.

As described on Slack, the regex versioner is currently causing bad PRs
such as [this](https://github.com/TheKevJames/experiments/pull/8) since
it can not properly track the current version. By parsing the `range`
values with the same logic as the other version strings, eveverything
should match up properly.

The regex versioner supports arbitrary, user-defined versioning
methods; it provides building blocks in the way of interacting capture
groups within a user-defined regex which can be combined to support
arbitrary use-cases.

Uses a new `versionConfig` option to configure this scheme -- this
feature is enabled dynamically for any new versioner which includes the
optional `configure?(new_config: string)` interface. Warns if used with
an invalid scheme.

Closes #4317