[Issue 12735] imports via mixin template become public imports

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=12735

--- Comment #4 from det <2k...@gmx.net> ---
surprisingly, this issue is still not fixed in DMD 2.071.1. surprising, because
if the template would be mixed in the same module, the import would be
invisible.

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