We added the DIB_distro_DISTRIBUTION_MIRROR arguments with
I92964b17ec3e47cf97e3a3091f054b2a205ac768 as a way that we could
source a list of mirrors and then have the distro elements choose
which one applied to them.
However, this hasn't worked out to be so useful. The
openstack-ci-mirrors element is working as a mirror setup script -- it
translates the openstack CI mirror list variables into the generic
"DIB_DISTRIBUTION_MIRROR" as appropriate for each distro's build.
Also, it turns out there's other things that need to be done, such as
turning off gpg checking, which mean the idea of "just export
variables" hasn't turned out as valid ... you need actual code
involved to get it right.
AFAICT we never actually documented these, and they do not seem to be
in use. They have caused considerable confusion when dealing with new
platforms as we try to keep consistency. Remove them.
[1] http://codesearch.openstack.org/?q=DIB_.*_DISTRIBUTION_MIRROR&i=nope&files=&repos=
Change-Id: Ifc4ab700631ffdfbe790068558f670f9a11dde5e
3457d2f8e8