RFR: forge: fix check in GitLabRepository.commit

[Erik Helin]

Hi all,

please review this small patch that fixes a bad check in `GitLabRepository.commit`.

Thanks,
Erik

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Commit messages:
 - forge: fix check in GitLabRepository.commit

Changes: https://git.openjdk.java.net/skara/pull/910/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=910&range=00
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/910.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/910/head:pull/910

PR: https://git.openjdk.java.net/skara/pull/910