[Issue 18606] [REG2.072] "cannot append type const(T) to type T[]" in .dup

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18606

--- Comment #2 from Vladimir Panteleev <dlang-bugzilla at thecybershadow.net> ---
The commits are big too, but if it helped, I can bisect it down to the commit.

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