#2471 multiple invocations of subscription after upsertLocal()

[styx0r]

This PR contains:

IMPROVED TESTS revealing a potential bug

Describe the problem you have without this PR

Issue #2471:

• when upsert a localDocument subscriptions invoked twice
• the implemented test additionally revealed that subscribing with
  .$.subscribe on a document it is directly invoked already,
  not sure whether this is intended

Todos

• Tests
• Changelog
• Bugfix

[pubkey]

Thanks for adding the test. Can you fix the linting so that the CI runs the tests and does not stop before?

[styx0r]

Thanks for adding the test. Can you fix the linting so that the CI runs the tests and does not stop before?

Yes sorry, I did not recognise this by myself. Now it failed exactly at the newly implemented test.

[pubkey]

Fixed at 2cf425f
Thank you for adding the test, this really helped.