RFR: Discard duplicate checks

[Robin Westberg]

Hi all,

Please review this minor change that discards multiple GitHub checks with the same name for the same commit. Skara never generates these, but they may appear from external sources.

Best regards,
Robin

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Commits:
 - 2108da84: Discard duplicates

Changes: https://git.openjdk.java.net/skara/pull/235/files
 Webrev: https://webrevs.openjdk.java.net/skara/235/webrev.00
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/235.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/235/head:pull/235

PR: https://git.openjdk.java.net/skara/pull/235