[Issue 20135] Tuple assignment incorrectly calls destructor on freshly postblitted structs

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20135

--- Comment #1 from Adam D. Ruppe <destructionator at gmail.com> ---
Specifically I'd like to thank Nick Rozinsky on IRC for being the one who
provided the initial report to me.

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