RFR: 1687: Workaround bug in GitLab where MR LIST API may server stale data

[Erik Joelsson]

This patch provides a workaround for a GitLab bug that we are currently encountering. The issue has been fixed upstream, but until we have it deployed in our instance, we need to work around it.

GitLab sometimes serves stale data for merge requests from list queries. For Skara this means that label changes aren't always picked up. I have verified that up-to-date data is always received when fetching single merge requests by ID, so the patch simply re-fetches MRs to make sure the data is always up to date. I'm also adding logging to track when stale data is detected. This will help us verify (at least empirically) when the GitLab issue resolved for us.

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Commit messages:
 - Adjusted comments and log message
 - SKARA-1687

Changes: https://git.openjdk.org/skara/pull/1427/files
 Webrev: https://webrevs.openjdk.org/?repo=skara&pr=1427&range=00
  Issue: https://bugs.openjdk.org/browse/SKARA-1687
  Stats: 38 lines in 1 file changed: 38 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/skara/pull/1427.diff
  Fetch: git fetch https://git.openjdk.org/skara pull/1427/head:pull/1427

PR: https://git.openjdk.org/skara/pull/1427