std.parallelism taskPool.map example throws exception

[Jay Norwood via Digitalmars-d-learn]

This appears to work ... at least, no exception:

	auto sm = File(fn).byLine(KeepTerminator.no)
		.map!"a.chomp"()
		.map!"a.idup"()
		.map!(to!double)
	    .map!"a.log10"()
		.sum();

	writeln("sum=",sm);