[Issue 13253] use more scoped imports in phobos

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13253

--- Comment #10 from Илья Ярошенко <ilyayaroshenko at gmail.com> ---
See also:
https://github.com/D-Programming-Language/phobos/pull/2700
https://github.com/D-Programming-Language/phobos/pull/2701

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