shlex.split('-D ""') left a bare -D that gcc resolves by eating the
next flag; the funnel now warns and drops it for every consumer, which
also retires raise_on_empty_arg_flags, whose staged ESP8266 caller no
longer has anything to catch.
cancel_futures only drops queued jobs, and the non-daemon workers are
joined at interpreter exit, so a Ctrl-C during the ESP-IDF toolchain
fetch waited out every in-flight archive. The tracker each job reports
through now checks a cancellation flag set when the wait raises, so
downloads abort at their next progress tick and the resumable .part
files keep the bytes already fetched.
The wave-deferral test stubs _content_lengths instead of issuing real
HEAD requests that passed only by failing, the dead hasattr branch in
the HEAD-probe test is gone, and the .C suffix comment names the SCons
divergence instead of claiming parity.
J. Nick Koston