When trying to clone a SVN repo, it appears that the clone operation has hung, when it really is just doing something that takes a long time. I would propose that a message be printed out to the user letting them know this operation could take a long time. Something as simple as:
$ hg clone svn+http://svn.python.org/projects/python python-hg <Print what operation is going on>. This could take a while. }}}
As of now, after you enter in the clone command, the terminal appears to hang.
Also, I'm doing this on windows 7 machine, from the command line.
I'm using Rev f28e0f54a6ef30f6eef007e69c1736f667592a9b on default.