
This fixes cases where "not not <command>" is supposed to return only the error codes 0 or 1, but after efee57925c3f46c74c6697, it passed the original error code through. This was visible on AIX in the shtest-output-printing.py testcase, where 'wc' returns 2, while it returns 1 on other platforms, and the test required "not not" to normalize it to 1.