Bypass repo server if missing pip upgrade packages
Bypass repo server if missing pip upgrade packages

The function get_pip upgrades the pip packages for pip. If OSA is
updated to require newer versions these may not be present on the repo
server and this will cause bootstrap-ansible.sh to fail.

Update the get_pip function to fallback on calling pip with the
--isolated flag when pip is installed and the pip packages are being
upgraded.

Change-Id: Ifa644b9bf6aa8b20028eb0257c40fe20f3ab1a3b

mrda/openstack-ansible,Logan2211/openstack-ansible,Logan2211/openstack-ansible,weezer/openstack-ansible,mancdaz/openstack-ansible,bunchc/openstack-ansible,mrda/openstack-ansible,os-cloud/os-ansible-deployment,cfarquhar/openstack-ansible,cloudnull/os-ansible-deployment,major/openstack-ansible,BjoernT/openstack-ansible,stackforge/os-ansible-deployment,robb-romans/openstack-ansible,yanyao/newton,major/openstack-ansible,os-cloud/os-ansible-deployment,BjoernT/openstack-ansible,mancdaz/openstack-ansible,BjoernT/os-ansible-deployment,openstack/openstack-ansible,stackforge/os-ansible-deployment,major/os-ansible-deployment,yanyao/openstack-ansible,yanyao/openstack-ansible,BjoernT/os-ansible-deployment,cfarquhar/openstack-ansible,cloudnull/os-ansible-deployment,BjoernT/os-ansible-deployment,openstack/openstack-ansible,mrda/openstack-ansible,bunchc/openstack-ansible,yanyao/newton,weezer/openstack-ansible,major/os-ansible-deployment,robb-romans/openstack-ansible