Should probably be

gem 'fog-openstack', '~> 0.1', '>= 0.1.7'

The pinning of fog-core to 1.36.0 currently prevents the ~> 0.1 matcher from matching 0.1.7. If fog-core is updated to over 1.40 (either specifically, or unpinned) then we'll automatically inherit a newer version of fog-openstack too.

Well, since this breaks the functionality quite bad, I think this should get priority.

Note that Liberty is the minimal version of Openstack still supported (http://releases.openstack.org/), so Foreman should probably be compatibable with it.

Dominic Cleal wrote:

The pinning of fog-core to 1.36.0 currently prevents the ~> 0.1 matcher from matching 0.1.7. If fog-core is updated to over 1.40 (either specifically, or unpinned) then we'll automatically inherit a newer version of fog-openstack too.

btw, another thing to note is that nothing ensures you will get the latest version of 0.1 - see https://github.com/bundler/bundler/issues/3089#issuecomment-48533609 for example.
Therefore, it is probably a good idea to change the requirement anyway.