Remove distlib from OpenStack constraints
Remove distlib from OpenStack constraints

It raised side effects wih Alpine [1].

[1] https://build.opnfv.org/ci/job/functest-core-docker-build-amd64-master/933/console

Change-Id: Ic922c2b56afe67f2f3e436c562c045f4d0fdbef4
Signed-off-by: Cédric Ollivier <d48310251a4a484d041bc5d09a9ac4d86d20f793@orange.com>

opnfv/functest,opnfv/functest