Interestingly, last Friday, I was commenting on pexpect support with respect to supporting ipython. (As I understand it, pexpect is used for testing ipython.)
In principle, this doesn't look so bad for an interested person to explore. It's a very nice self-contained project that would consist of identifying appropriate third-party jars, such as for JPty; glueing together with Python code using this Java functionality; and publishing into PyPI. At some point, including depending on the jars licensing, we could explore incorporating into Jython directly, say in a 2.7.1 or later release.
There was more discussion here on the jython-dev mailing list about termios:
In a nutshell, true support of fork is not feasible until the JVM supports it. And that support would be very hard.