[Integrated] RFR: Failed merge commit message should not throw, but report a failure

[Robin Westberg]

Changeset: 1ba3260b
Author:    Robin Westberg <rwestberg at openjdk.org>
Date:      2020-04-16 06:54:49 +0000
URL:       https://git.openjdk.java.net/skara/commit/1ba3260b

Failed merge commit message should not throw, but report a failure

Reviewed-by: ehelin

! bots/pr/src/main/java/org/openjdk/skara/bots/pr/PullRequestCheckIssueVisitor.java
! bots/pr/src/test/java/org/openjdk/skara/bots/pr/MergeTests.java