writeln() sometimes double prints from main() if I run a thread checking for input?

[Timothy Foster via Digitalmars-d-learn]

On Wednesday, 30 August 2017 at 11:28:49 UTC, Stefan Koch wrote:
> On Wednesday, 30 August 2017 at 10:55:20 UTC, Timothy Foster 
> wrote:
>> On Wednesday, 30 August 2017 at 10:44:43 UTC, Ivan Kazmenko 
>> wrote:
>>> [...]
>>
>> import std.stdio, core.thread;
>>
>> void main(){	
>> 	auto thread = new Thread(&func).start;
>>         writeln("Output");
>> 	writeln("Output2");
>> 	writeln("Output3");
>> 	while(true){}
>> }
>>
>> void func(){
>>     foreach(line; stdin.byLineCopy){}
>> }
>>
>> The printout from the above typically gives me:
>> Output
>> Output2
>> Output2
>> Output3
>>
>> I've narrowed down the issue. I just don't know what to do 
>> about it.
>
> I cannot reproduce this. what os / compiler are you using ?

Windows 7 Ultimate 64-bit
DMD32 D Compiler v2.075.1

The issue is inconsistent. Sometimes it'll print as it should, 
sometimes it'll double the first line, sometimes the second, 
sometimes both the first and second.