RFR: 1563: The method 'CheckRun#updateMergeReadyComment' shouldn't update the comment if the comment has not changed [v4]

[Zhao Song]

> Do not update comment if the comment already exists.

Zhao Song has updated the pull request incrementally with one additional commit since the last revision:

  Adjusted some log

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Changes:
  - all: https://git.openjdk.org/skara/pull/1386/files
  - new: https://git.openjdk.org/skara/pull/1386/files/3021e803..0bd093a9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=skara&pr=1386&range=03
 - incr: https://webrevs.openjdk.org/?repo=skara&pr=1386&range=02-03

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/skara/pull/1386.diff
  Fetch: git fetch https://git.openjdk.org/skara pull/1386/head:pull/1386

PR: https://git.openjdk.org/skara/pull/1386