[Issue 6138] Using dirEntries and chdir() can have unwanted results

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=6138

--- Comment #7 from Timothee Cour <timothee.cour2 at gmail.com> ---
just hit that bug again, but differently:
```
chdir(foo);
auto files=dirEntries(dirSrc, "*.d",
SpanMode.depth).filter!(a=>a.isFile).map!(a=>dir.buildPath(a.name)).array;
```
crashed similarly

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