RFR: Add additional sync label tests, adjust the implementation to match

[Erik Helin]

On Wed, 24 Feb 2021 07:48:05 GMT, Robin Westberg <rwestberg at openjdk.org> wrote:

> Adjust the implementation of the sync label rules to match expectations.

Looks good!

@rwestberg you might want to fix the test failure though ��

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Marked as reviewed by ehelin (Reviewer).

PR: https://git.openjdk.java.net/skara/pull/1033