run-tests: fix get port to try differing ports
The code was moving its offset each time through the loop,
but because it failed to update port, the port was not
going to be available...
httpclient: update to
938f2107d6e2 of httpplus
This enhances proxy support in httpclient a little bit, though I don't
know that we used that functionality at all. It also switches httpplus
to using absolute_import.