use an unqualified path to python2
use an unqualified path to python2

seankelly/buildbot-infra,djmitche/buildbot-infra,seankelly/buildbot-infra,buildbot/buildbot-infra,ewongbb/buildbot-infra,seankelly/buildbot-infra,ewongbb/buildbot-infra,buildbot/buildbot-infra,buildbot/buildbot-infra,djmitche/buildbot-infra,djmitche/buildbot-infra