ORA remote initialization stalls on windows

[mih]

Filing here, because the datalad-core implementation has no ambition to work on windows.

A new test added with #653 performs a create-push-clone roundtrip over a RIA store, using different clients and a unix-server target. It documents that this stalls on windows. A similar stalling has been reported in the datalad office hour by a datalad user on windows.

The test case #653 may be a suitable reproducer debugging these (or these two) issues.

[mih]

The cause seems to be datalad/datalad#7491, which is presumably fixed by a series of patched present in datalad-ria.

[mih]

These patches (alone) do not cut it. I found that using the code from #596 to replace the Popen call in SSHRemoteIO.__init__ leads to a usable authentication prompt, on windows, with no stdin connected to the terminal. I guess that is the path forward. Wait for #596 to land and then patch RIA/ORA to use it.