Comment 1 for bug 1625693

I'm able to work around this issue with puppet roughly like so;

apt::pin { 'fuel-plugin-tesora-dbaas-1.9.0':
    priority => 1100,
    label => 'fuel-plugin-tesora-dbaas',
    release_version => '1.9',
}

which yields a apt preferences file:
root@node-2:~# cat /etc/apt/preferences.d/fuel-plugin-tesora-dbaas-1.9.0.pref
# This file is managed by Puppet. DO NOT EDIT.
Explanation: : fuel-plugin-tesora-dbaas-1.9.0
Package: *
Pin: release v=1.9, l=fuel-plugin-tesora-dbaas
Pin-Priority: 1100

I create a fuel task to run just this 1 puppet resource.
I'm able to run this task early enough to prevent flip-flopping between versions.
For example, Heat installation will cause python-troveclient package to be installed, and it will be Tesora version of this package from the get-go. As it was in 8.0.