cinder upload volume operation doesn't work with multiple cinder stores

[Rajat Dhasmana]

Env: Glance is configured to use cinder as it's backend with multiple stores enabled.

When we upload a volume from cinder to glance, we face the following error and image never gets created.

glanceclient.exc.HTTPBadRequest: HTTP 400 Bad Request: Invalid location

This is because glance expected a location URI in the format
cinder://<store-id>/<vol-id>
instead cinder sends the URI
cinder://<vol-id>

Cinder cannot provide store-id since it doesn't have info about the glance stores and in which store the volume will be uploaded as an image.
Glance can handle this case by updating the location received from cinder (startswith("cinder://") and update it in the new format.