Filenames with NUL bytes in them are incorrectly accepted

[dlangBugzillaToGithub]

elronnd reported this on 2020-02-20T21:44:42Z

Transfered from https://issues.dlang.org/show_bug.cgi?id=20590

Description

Sample code:

import std.stdio;                                                                                                                      
import std.file: readText;

void main() {
        writeln(readText("foo.txt\0blah"));
}

The file 'foo.txt\0blah' /can't/ exist on unix (idk about windows), but foo.txt exists and is read.