Fix a missed argument from a previous refactor

Region name support got changed a little while ago, and a call that
should now be a keyword argument style stayed as a positional ... which
means that we lost region name support for clouds with more than one
region. (it treated all of them like the first region)

Change-Id: I666758a775b8fc8e03b7e9ddd3aa494c13505612
Merge "Fix a missed argument from a previous refactor"