RFR: 2082: Use correct .jcheck/conf in AdditionalConfiguration.java [v4]

[Erik Duveblad]

> Hi all,
> 
> please review this patch that ensures that we pass the correct `.jcheck/conf` to [AdditionalConfiguration.java](https://github.com/openjdk/skara/blob/master/bots/pr/src/main/java/org/openjdk/skara/bots/pr/AdditionalConfiguration.java). The `.jcheck/conf` should either come from the "overriding" `.jcheck/conf` (if the PR bot is configured to use that) or the pull request's target branch.
> 
> I have added that test that passes with this patch but fails without it.
> 
> Thanks,
> Erik

Erik Duveblad has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains ten commits:

 - Merge master
 - optimize
 - final review
 - refactor
 - whitespace
 - do not throw from checkStatus
 - Merge branch 'master' into pr-correct-jcheck-conf
 - Fix .jcheck/conf parsing in multiple places
 - 2082

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Changes: https://git.openjdk.org/skara/pull/1578/files
 Webrev: https://webrevs.openjdk.org/?repo=skara&pr=1578&range=03
  Stats: 176 lines in 8 files changed: 102 ins; 7 del; 67 mod
  Patch: https://git.openjdk.org/skara/pull/1578.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1578/head:pull/1578

PR: https://git.openjdk.org/skara/pull/1578