'Grabs the storage backend for the supplied store name
or raises an HTTPBadRequest (400) response
:param request: The WSGI/Webob Request object
:param scheme: The backend store scheme
:raises HTTPBadRequest: if store does not exist'

def get_store_or_400(self, request, scheme):

    try:
        return store.get_store_from_scheme(scheme)
    except store.UnknownScheme:
        msg = (_('Store    for    scheme    %s    not    found') % scheme)
        LOG.warn(msg)
        raise HTTPBadRequest(explanation=msg, request=request, content_type='text/plain')
