RFR: Handle empty GitLab merge requests

[Robin Westberg]

Hi all,

Please review this small change that allows empty GitLab merge requests to be inspected.

Best regards,
Robin

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Commit messages:
 - Handle empty GitLab merge requests

Changes: https://git.openjdk.java.net/skara/pull/633/files
 Webrev: https://webrevs.openjdk.java.net/skara/633/webrev.00
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/633.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/633/head:pull/633

PR: https://git.openjdk.java.net/skara/pull/633