Following the commit fb2c434c2461a25193067104de766fc1142a6024 in
the cinder repo the --force option to upload-to-image is ignored
by default. To enable it the config option enable_force_upload
must be set to true.
The help text for upload-to-image in the python cinderclient
should remind user that --force may not work in some cloud now.
Closes-Bug: #1611667
Change-Id: Ib56fb2016d933a9bbbcb0185c50e33d2166b34e6