RFR: 453: Merge commit not included in notification email

[Robin Westberg]

Hi all,

Please review this change that properly filters out commits brought in through a merge PR when creating a mailing list
notification email.

Best regards,
Robin

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Commit messages:
 - Filter out commits brought in through a merge PR

Changes: https://git.openjdk.java.net/skara/pull/710/files
 Webrev: https://webrevs.openjdk.java.net/skara/710/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-453
  Stats: 205 lines in 2 files changed: 190 ins; 5 del; 10 mod
  Patch: https://git.openjdk.java.net/skara/pull/710.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/710/head:pull/710

PR: https://git.openjdk.java.net/skara/pull/710