RFR: Stop throwing when unable to find a matching PR

[Robin Westberg]

Hi all,

Please review this change that stops throwing an exception when failing to match a change to an existing PR in the PR-only mode, as this is not very useful.

Best regards,
Robin

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Commits:
 - ae0a90ec:	Stop throwing when unable to find a matching PR

Pull request:
https://git.openjdk.java.net/skara/pull/142

Webrev:
https://webrevs.openjdk.java.net/skara/142/webrev.00

Patch:
https://git.openjdk.java.net/skara/pull/142.diff

Fetch command:
git fetch https://git.openjdk.java.net/skara pull/142/head:pull/142