[Issue 1983] Delegates violate const

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=1983

--- Comment #20 from Stanislav Blinov <stanislav.blinov at gmail.com> ---
It was: https://issues.dlang.org/show_bug.cgi?id=16095

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