[tex-live] Windows 7: pretest tlmgr freezes when trying to load remote repository

[Joel C. Salomon]

Trying TeX Live 2012 pretest under Windows 7, I did a "portable"
minimal installation successfully. Running tlmgr to update the system,
it freezes after trying to "load default repository".

This is not a proxy issue: if I do not have http_proxy set correctly,
I get an error message without the program freezing.

Similarly, if I choose to "load default net repository", I get an
error message for the version mismatch, without a freeze.

Is there something I can do to help narrow down the source of this problem?

---Joel