RFR: 2015: Initial run of PR IssueBot misses issue updates

[Zhao Song]

Currently, if pullRequestBot is down for more than 10 minutes and during that time, if users make changes to some issues, than the update activities would not trigger CheckWorkItem after the bot restarts.

To solve this problem, In this patch, after the bot restarts, in the initial run, pullRequestBot would make CheckWorkItem compare both prMetaData and issueMetaData.

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Commit messages:
 - SKARA-2015

Changes: https://git.openjdk.org/skara/pull/1554/files
 Webrev: https://webrevs.openjdk.org/?repo=skara&pr=1554&range=00
  Issue: https://bugs.openjdk.org/browse/SKARA-2015
  Stats: 42 lines in 5 files changed: 12 ins; 17 del; 13 mod
  Patch: https://git.openjdk.org/skara/pull/1554.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1554/head:pull/1554

PR: https://git.openjdk.org/skara/pull/1554