Cool.  We implemented our own version as a straight-up native module (https://java.net/projects/ips/sources/pkg-gate/content/src/modules/pspawn.c), and our Popen replacement is not at present a complete replacement for the one in the stdlib, but it does what we need it to do.  We'd absolutely switch if it came in to the stdlib, though, and I think there would be plenty of programs that would benefit from it (certainly a number of large Python programs in Solaris have run into exactly this problem).