$ pyside-uic main.ui -o main.py
An unexpected error occurred.
Check that you are using the latest version of PySide and report the error to
http://bugs.openbossa.org, including the ui file used to trigger the error.
$ echo $?
0

If you are using a Makefile to run pyside-uic it thinks that the command succeeded.

In addition to not exiting cleanly, the file main.py exists and has some code in it, but it is incomplete.