Fix centos-source trove image building
Fix centos-source trove image building

It appears Trove still depends on MySQL-python.
Restore the workaround for broken Percona repo.

Closes-Bug: #1531371
Related-Bug: #1526129
Change-Id: I1781fee14e17a6b7cbb2cf8dae639e049698b9e6

intel-onp/kolla,rahulunair/kolla,mandre/kolla,mandre/kolla,GalenMa/kolla,stackforge/kolla,openstack/kolla,nihilifer/kolla,GalenMa/kolla,limamauricio/mykolla,coolsvap/kolla,limamauricio/mykolla,nihilifer/kolla,dardelean/kolla-ansible,stackforge/kolla,negronjl/kolla,dardelean/kolla-ansible,limamauricio/mykolla,mrangana/kolla,toby82/kolla,intel-onp/kolla,tonyli71/kolla,coolsvap/kolla,mandre/kolla,negronjl/kolla,toby82/kolla,negronjl/kolla,dardelean/kolla-ansible,mrangana/kolla,tonyli71/kolla,toby82/kolla,stackforge/kolla,openstack/kolla,coolsvap/kolla,rahulunair/kolla