[skara] RFR: pr: fix configuration of forks

[Erik Helin]

Hi all,

please review this small patch that fixes how forks are configured for the `/backport` commit command.

Thanks,
Erik

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Commit messages:
 - pr: fix configuration of forks

Changes: https://git.openjdk.java.net/skara/pull/1097/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1097&range=00
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/1097.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1097/head:pull/1097

PR: https://git.openjdk.java.net/skara/pull/1097