I464bc2b88123a012cd12213beac4b572c3c20a56 introduced a second call to
``qemu-img`` that can easily be collapsed into one with the addition of
a new call within the disk_api.
Conflicts:
nova/tests/unit/virt/libvirt/test_driver.py
NOTE(s10): The conflict was due to not having change
Ic853743573aa0b74d5d2c5b8b47252b875d5f7ef in Queens.
NOTE(s10): Another conflict was due to not having change
I11e329ac5f5fe4b9819fefbcc32ff1ee504fc58b in Pike.
Related-Bug: #1785827
Change-Id: Ibfd0527ed79f60282b542034d7cb97b424becba3
(cherry picked from commit d41ea9d878)
(cherry picked from commit d085c8fe53)