RFR: 447: Sponsoring should only require committer status

[Erik Helin]

Hi all,

please review this small patch that ensures that Committers can sponsor patches.

Testing:
- [x] `make test` passes on Linux x64

Thanks,
Erik

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Commit messages:
 - 447

Changes: https://git.openjdk.java.net/skara/pull/691/files
 Webrev: https://webrevs.openjdk.java.net/skara/691/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-447
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/691.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/691/head:pull/691

PR: https://git.openjdk.java.net/skara/pull/691