RFR: 958: Add test cases for known corner cases for synclabel bot

[Robin Westberg]

Add special exclude list, proper BPR detection for 9+, and tests.

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Commit messages:
 - Add special exclude list, proper BPR detection for 9+, and tests

Changes: https://git.openjdk.java.net/skara/pull/1109/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1109&range=00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-958
  Stats: 306 lines in 2 files changed: 301 ins; 1 del; 4 mod
  Patch: https://git.openjdk.java.net/skara/pull/1109.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1109/head:pull/1109

PR: https://git.openjdk.java.net/skara/pull/1109