Avoid overwriting python_version_ext or ruby_version_ext if pre-set in fabricrc.txt. chapmanb/bcbio-nextgen#58
Avoid overwriting python_version_ext or ruby_version_ext if pre-set in fabricrc.txt. chapmanb/bcbio-nextgen#58

kdaily/cloudbiolinux,chapmanb/cloudbiolinux,AICIDNN/cloudbiolinux,elkingtonmcb/cloudbiolinux,lpantano/cloudbiolinux,rchekaluk/cloudbiolinux,averagehat/cloudbiolinux,rchekaluk/cloudbiolinux,chapmanb/cloudbiolinux,joemphilips/cloudbiolinux,rchekaluk/cloudbiolinux,averagehat/cloudbiolinux,kdaily/cloudbiolinux,pjotrp/cloudbiolinux,averagehat/cloudbiolinux,elkingtonmcb/cloudbiolinux,pjotrp/cloudbiolinux,rchekaluk/cloudbiolinux,heuermh/cloudbiolinux,AICIDNN/cloudbiolinux,lpantano/cloudbiolinux,kdaily/cloudbiolinux,kdaily/cloudbiolinux,AICIDNN/cloudbiolinux,elkingtonmcb/cloudbiolinux,lpantano/cloudbiolinux,averagehat/cloudbiolinux,joemphilips/cloudbiolinux,heuermh/cloudbiolinux,chapmanb/cloudbiolinux,heuermh/cloudbiolinux,joemphilips/cloudbiolinux,pjotrp/cloudbiolinux,elkingtonmcb/cloudbiolinux,joemphilips/cloudbiolinux,chapmanb/cloudbiolinux,heuermh/cloudbiolinux,AICIDNN/cloudbiolinux,pjotrp/cloudbiolinux