D lang compilers have an option -release (or similar) which turns off
asserts, contracts, and other runtime type checking. This patch wires
that up to the b_ndebug flag.
Fixes#7082
That syntax is invalid, since decimal numbers should never have a
leading zero and octal numbers use the `0o` prefix instead.
This matches Python 3 syntax which does not accept it:
$ python3
>>> 0123
File "<stdin>", line 1
0123
^
SyntaxError: invalid token
>>>
Add a "failing" test case to confirm this property is preserved and no
regressions are introduced in this area.