Open3.popen3(...) is broken in 1.9 mode

It appears Open3.popen3(...) is broken on JRuby in 1.9 mode.
On 1.8.7, it returns three arguments (stdin, stdout, and stderr).
On 1.9.X, it returns (stdin, stdout, stderr, and a thread).

You can use the thread argument to access a Process::Status object,
and the PID of the spawned command.

To reproduce:

stdin, stdout, stderr, thr = Open3.popen3 "ls"
thr.value # => NoMethodError (called on nil)

Thanks!