[6.1] pbr==0.11 is required

[Dmitry Teselkin]

A lot if periodic jobs fail because pbr==0.10.0 was used during the tests. This version was used because we use that version of package (from private repositories).

Jobs that fail:
* http://logs.mosi.mirantis.net/periodic/periodic-neutron-pep8-mos61/ca9d9a6/
* http://logs.mosi.mirantis.net/periodic/periodic-neutron-python27-mos61/3487383/
* http://logs.mosi.mirantis.net/periodic/periodic-keystone-pep8-mos61/b5d8bd9/
* http://logs.mosi.mirantis.net/periodic/periodic-sahara-pep8-mos61/8cb1d5c/
* http://logs.mosi.mirantis.net/periodic/periodic-ceilometermiddleware-pep8-mos61/6cbef08/
* http://logs.mosi.mirantis.net/periodic/periodic-oslo.messaging-pep8-mos61/423ddd6/
* http://logs.mosi.mirantis.net/periodic/periodic-nova-pep8-mos61/447d48c/
* http://logs.mosi.mirantis.net/periodic/periodic-ceilometer-pep8-mos61/0b2bf36/
* http://logs.mosi.mirantis.net/periodic/periodic-cinder-pep8-mos61/eb562e0/

[Dmitry Teselkin (teselkin-d)]

https://mirantis.jira.com/browse/MOSI-256

[Artur Kaszuba (akaszuba)]

This bug is related to constraints in mos-requirements, please decide what pbr version should be used for 6.1 tests and update constraints.

[Denis Meltsaykin (dmeltsaykin)]

This bug is not relevant anymore, as we pinned all the dependencies we needed. Closing as Invalid.