[kovidgoyal]

Yes, you should end the *_prefix variables with a forward slash.

Those errors indicate that an attempt to either read or write or allocate a network socket is being interrupted. The most common cause of this is if the process has run out of available file handles. Make sure your subprocess calls close the stdout/stdin/stderr file handles immediately after using them.

EDIT: And you can attach the patches here or better, open a bug report and attach them to it.