Adjusts vagrant shared folder behavior under libvirt
Adjusts vagrant shared folder behavior under libvirt

The NFS strategy for mounting /vagrant in the development machine should
only take effect if the libvirt provider is currently active. Let's
reference the `override` pragma, documented here [0], to achieve.

Supplements changes in #1561. Closes #1582.

[0] https://www.vagrantup.com/docs/providers/configuration.html

conorsch/securedrop,garrettr/securedrop,garrettr/securedrop,heartsucker/securedrop,heartsucker/securedrop,ageis/securedrop,ehartsuyker/securedrop,micahflee/securedrop,micahflee/securedrop,ehartsuyker/securedrop,micahflee/securedrop,ehartsuyker/securedrop,conorsch/securedrop,heartsucker/securedrop,ageis/securedrop,conorsch/securedrop,conorsch/securedrop,ehartsuyker/securedrop,heartsucker/securedrop,garrettr/securedrop,ageis/securedrop,garrettr/securedrop,ehartsuyker/securedrop,ehartsuyker/securedrop,ageis/securedrop,heartsucker/securedrop,conorsch/securedrop,micahflee/securedrop