V1.10.b1: Within _boot.py is dupterm() set for uart 0. If later dupterm is set for the same uart, keyboard entry is blocked. That seems to have cause many of the non-responding REPL complaints with v 1.10.b1, when this second os.dupterm() was still in boot.py. Obviously, that can be solved by deleting boot.py.

I raise that issue just to put it on the To-Do-List.