Changes to repo fixture for regex merge branch.
Config setting: pick master branch via regex
Merge regex-merge-branch (#45) into master

Config setting: pick merge branch via regex

We had an issue where we kept trying to merge master into hotfixes
that were based on stable. This caused merge conflicts. Now, we
examine the branch we're testing. We can now configure cimpler to
merge stable instead if the branch we're testing begins with
"hotfix-".