[Issue 19264] byCodeUnit should compare with strings

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19264

--- Comment #1 from Steven Schveighoffer <schveiguy at yahoo.com> ---
It shouldn't matter the constancy of the original.

This should also work:

assert("hello".byCodeUnit == "hello".dup.byCodeUnit);

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