Note that this includes seemingly-unrelated test changes because we
were actually skipping the snapshot_running test for libvirt, which
has been a bug for years. In that test case, when we went to look
for image_meta.disk_format, that attribute was not set on the o.vo
object, which raised a NotImplementedError. That error is also checked
by the test to skip the test for drivers that do not support snapshot,
which meant that for libvirt, we haven't been running that case
beyond the point at which we create snapshot metadata and trip that
exception. Thus, once removing that, there are other mocks not in
place that are required for the test to actually run. So, this adds
mocks for qemu_img_info() calls that actually try to read the file on
disk, as well as the privsep chown() that attempts to run after.
Change-Id: Ie731045629f0899840a4680d21793a16ade9b98e
(cherry picked from commit d5a631ba7791b37e49213707e4ea650a56d2ed9e)
(cherry picked from commit 8c5929ff5156d5409d41872f1b8ee0abb04f35a8)
(cherry picked from commit d2d3b2c9e87fe2247a34a776310221c8b12be515)
(cherry picked from commit 77dfa4f6f3c39048b5d3bb9eb2b14dd6998b406b)
(cherry picked from commit e6f4503fe3e20c3fb8afef0aa944d4994665786b)