During a merge from branch on the same repository as current copy:
svn merge -r17007:17249 http://hostname/svn/path
I got the error: svn: Malformed URL for repository. The fix is to add user name in SVN URL:
svn merge -r17007:17249 http://dcieslak@hostname/svn/path
Is this a Subversion bug? Probably the problem is that my username placed in SVN config file has form: domainname\username. Maybe SVN merge cannot handle that format?