Wait for the child process to terminate before ending the test, so that the
regrtest cleanup code doesn't get an error when it tries to delete the
temporary CWD.

Py_AddPendingCall() for the first signal to fix a deadlock on reentrant or
parallel calls. PyErr_SetInterrupt() writes also into the wake up file.

Also fix a typo and a misleading example (method used to describe function).

Issue #5057: fix a bug in the peepholer that led to non-portable pyc files between narrow and wide builds while optimizing BINARY_SUBSCR on non-BMP chars (e.g. "\U00012345"[0]).

Issue #11467: Fix urlparse behavior when handling urls which contains scheme specific part only digits.