Problem with string.whitespace and newline

[Michael Chen]

The following code cannot be compiled
string clean(string x)
{
        return join(split(x),whitespace);
}

The compile error is
Error   2       Error: template std.array.join(RoR,R) if (isInputRange!(RoR)
&& isInputRange!(ElementType!(RoR)) && isForwardRange!(R)) cannot
deduce template function from argument types
!()(string[],immutable(char[6u]))

However this line is fine
 join(split(x)," ");


The same problem happens when using newline. Is this a bug?

Best,
Mike