
Some older distros (like centos8 and xenial) don't support SNI in their easy_install implementations which are used to install setup_requires for python packages. PBR is a setup_requires for glean. We work around this problem when installing glean by preinstalling PBR with pip. Change-Id: Ie9f5c9ed06954cbe51f23fe8cca0655a931a5201