Fix redistribution of files w.r.t. offline nodes
Fix redistribution of files w.r.t. offline nodes

Currently, _RedistributeAncillaryFiles computes two lists: the list of
online nodes (for all files redistribution), and the list of
vm_capable nodes, for hypervisor-specific files. However, the
vm_capable list includes offline nodes too, leading to warning
messages:

  WARNING: Copy of file /etc/xen/xend-config.sxp to node node13.example.com failed: Node is marked offline

We fix this by trivially intersecting the vm_capable list with the
online one.

Signed-off-by: Iustin Pop <acf83a5274f31a43af6b914614365999469c1a31@google.com>
Reviewed-by: Bernardo Dal Seno <dcdd79c5479cb9d1329ec01d126f02cb045aa103@google.com>
Reviewed-by: René Nussbaumer <bc755ac45a0e799d1d490cba76febc56d80cc5fc@google.com>

andir/ganeti,andir/ganeti,mbakke/ganeti,ganeti-github-testing/ganeti-test-1,ganeti-github-testing/ganeti-test-1,yiannist/ganeti,leshchevds/ganeti,bitemyapp/ganeti,onponomarev/ganeti,yiannist/ganeti,apyrgio/ganeti,grnet/snf-ganeti,ganeti/ganeti,leshchevds/ganeti,onponomarev/ganeti,grnet/snf-ganeti,bitemyapp/ganeti,yiannist/ganeti,ganeti/ganeti,dimara/ganeti,ganeti/ganeti,apyrgio/snf-ganeti,apyrgio/snf-ganeti,mbakke/ganeti,andir/ganeti,dimara/ganeti,apyrgio/ganeti,leshchevds/ganeti,mbakke/ganeti