[Issue 13241] writeln no longer flushes stdout

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13241

--- Comment #7 from hsteoh at quickfur.ath.cx ---
Not sure if this is the right fix, since technically it should be a matter of
setting up stdout so that the flushing is done at OS level.

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