Copying file to /dev/null

[axricard via Digitalmars-d-learn]

``` D
import std;

void main()
{
    auto sourceName = deleteme ~ "source";
    auto source = File(sourceName, "w");
    source.write("source");
    copy(sourceName, "/dev/null");
}
```

The copy to /dev/null fails : 
`std.file.FileException@std/file.d(4348): /dev/null: Invalid 
argument`, which is a little surprising. Why would it be an 
invalid argument ?


The cp command for example doesn't raise any error :

```
cp source /dev/null
echo $?
0
```