I noticed an issue in prod, that I had not caught in testing. When running a stack-os-matrix job by hand, everything went well, but the test matrix was screwed up when called from another job. It seems that issue that the default value for the compiler matrix of system, devtoolset-3 is split on the comma when manually triggered but only on the space when called from another job. See: https://issues.jenkins-ci.org/browse/JENKINS-26490
I have reverted the changes to lsst-sqre/jenkins-dm-jobs and lsst-sqre/buildbot-scritps.