Session.stop not working on command shell

I'm trying to make my script end a created command shell session (using a cmd/unix/bind_perl payload). I get the result => 'success' output from calling the command in python, however the command shell doesn't appear to really be closing. It is causing complications with the actions that follow in the script, and I tried adding a call to list all the open sessions and the shell appeared in that list following the "successful" session termination. Any ideas?

Note: This issue does not occur for meterpreter sessions.