A workaround covering some of the more common cases is found in githash 596dcd6c097864f70f5231069733e6f747046301, improving upon earlier 92d6e37f62a54361be4b87e37cd64d8c4cfea5a1.
There certainly remain more ways to trick Rubber with working but questionable TeX code, but that's beside the point.
A workaround covering some of the more common cases is found in githash 596dcd6c097864f 70f5231069733e6 f747046301, improving upon earlier 92d6e37f62a5436 1be4b87e37cd64d 8c4cfea5a1.
There certainly remain more ways to trick Rubber with working but questionable TeX code, but that's beside the point.