Instead of changing the call semantics I would prefer some auto-detection:

* Something with :// is always a SVN URL and used as-is and can be either file://, http(s):// or svn:// or ssh:// URL
* Something without a :// must be checked as it could be one of
  * Working Copy with changes -> Need to build given revision or the HEAD+changes state if no revision is given. Affected hosts would be then determined by the changes. If there are no changes then is should build the hosts changed by the last commit.
  * SVN repo backend file space -> This is what we use now, need to build the given revision or the hosts changed by last commit.

We don't need to implement this straight away, but it would be nice to do a step into this direction. In any case we should not change the command line call semantics in an incompatible way.