[Integrated] RFR: 119: Attempt to rebase pull requests before running checks

[duke]

Changeset: dc663d36
Author:    Robin Westberg <rwestberg at openjdk.org>
Date:      2019-10-07 08:58:40 +0000
URL:       https://git.openjdk.java.net/skara/commit/dc663d36

119: Attempt to rebase pull requests before running checks

Reviewed-by: ehelin

! bots/pr/src/main/java/org/openjdk/skara/bots/pr/CheckRun.java
! bots/pr/src/main/java/org/openjdk/skara/bots/pr/IntegrateCommand.java
! bots/pr/src/main/java/org/openjdk/skara/bots/pr/PullRequestInstance.java
! bots/pr/src/test/java/org/openjdk/skara/bots/pr/CheckTests.java