tests: don't use "status" operand of dd in test-censor.t (issue6858)
Some implementations don't have this operand, let's just direct stderr into
/dev/null, that's pretty cross-platform.
Also specify bs=512 (the default for me), because the default might be
different on different systems. Other uses of dd in the tests do specify it, so
this is more consistent.
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)