Update purge_builds.py after bug 991230. (Also includes changes from bug 861733 that were never imported.). r=catlee
Update purge_builds.py after bug 991230. (Also includes changes from bug 861733 that were never imported.). r=catlee

--HG--
extra : rebase_source : 2b81dcae2693c1a88c013b02dbaa8669fb91528c

lundjordan/mozharness,simar7/build-mozharness,escapewindow/mozharness,escapewindow/mozharness,kartikgupta0909/gittest,simar7/build-mozharness,kartikgupta0909/build-mozharness,armenzg/build-mozharness,mozilla/build-mozharness,mrrrgn/build-mozharness,kartikgupta0909/mozilla-mozharness,mozilla/build-mozharness,kartikgupta0909/build-mozharness,kartikgupta0909/gittest,lissyx/build-mozharness,walac/build-mozharness,kartikgupta0909/mozilla-mozharness,mrrrgn/build-mozharness,lissyx/build-mozharness,lundjordan/mozharness,walac/build-mozharness,armenzg/build-mozharness