Python 3 removed deprecated string.lowercase.
Python 3 removed deprecated string.lowercase.

string.lowercase was deprecated in favour of string.ascii_lowercase
in early Python 2, and finally removed in Python 3.

Signed-off-by: Daniel P. Berrangé <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

libvirt/libvirt-sandbox,libvirt/libvirt-sandbox,libvirt/libvirt-sandbox