The following runs out of file handles on both Windows and Linux:

import std.stdio;

void main() {
    // Assumes you have a file called "foo.txt" laying around.  If you don't,
    // create one.
    while(1) {
        File("foo.txt");
    }
}

The following while loop body also does:

auto lines = File("foo.txt").byLine();

The following does not:

auto handle = File("foo.txt");

Marking as major because it silently breaks code in subtle ways.  I wrote several small programs that relied on reference counting to free the file handle, which seemed to work fine until one day I made them use a lot more file handles than they usually do.