(maint) Allow setting gem mirror via GEM_SOURCE env var
(maint) Allow setting gem mirror via GEM_SOURCE env var

cyberious/puppetlabs-reboot,puppetlabs/puppetlabs-reboot,ferventcoder/puppetlabs-reboot,cyberious/puppetlabs-reboot,ferventcoder/puppetlabs-reboot,puppetlabs/puppetlabs-reboot,aaam/puppetlabs-reboot,aaam/puppetlabs-reboot