RFR: 1281: Jcheck fails to run due to IllegalStateException

[Erik Joelsson]

This patch changes the reaction on a hg-tags jcheck failure in a PR from throwing IllegalStateException to just ignore with a log message. This is restoring the behavior to before [423](https://github.com/openjdk/skara/pull/423) for this particular check. See bug description for a more in depth explanation why this is needed.

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Commit messages:
 - SKARA-1281

Changes: https://git.openjdk.java.net/skara/pull/1258/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1258&range=00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-1281
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/1258.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1258/head:pull/1258

PR: https://git.openjdk.java.net/skara/pull/1258