critical(hangs):IO.popen allows the io to be closed inside the block
unstable(JRUBY-4171,linux,intermittent failure):IO.popen writes to a write-only pipe
fails:IO.popen starts returns a forked process if the command is -
windows(JRUBY-4701):IO.popen returns the IO if no block given
windows(JRUBY-4814):IO.popen reads from a read-only pipe
fails(JRUBY-5663):IO.popen yields an instance of a subclass when called on a subclass
fails(JRUBY-5663):IO.popen returns an instance of a subclass when called on a subclass
fails(JRUBY-5663):IO.popen with a leading Array parameter uses a trailing Hash in the Array for spawn-like settings
