RFR: 550: "branch has unmerged commits" message could be clarified by the bot

[Robin Westberg]

Hi all,

Please review this change that improves the final integrated message.

Best regards,
Robin

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Commit messages:
 - Add a notice about the closed message.
 - Only show up to 10 commits in the final integration message

Changes: https://git.openjdk.java.net/skara/pull/794/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=794&range=00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-550
  Stats: 33 lines in 3 files changed: 26 ins; 0 del; 7 mod
  Patch: https://git.openjdk.java.net/skara/pull/794.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/794/head:pull/794

PR: https://git.openjdk.java.net/skara/pull/794