[Issue 20328] [REG 2.089 beta] deprecation message about Nullable.get in isInputRange

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20328

--- Comment #7 from FeepingCreature <default_357-line at yahoo.de> ---
adam_d_ruppe on IRC said to always suppress deprecations in traits… the more I
think about it, the more I think this may actually be the right way to go.

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