Comment 4 for bug 1126115

Success command is now wrapped in a separate script that uses the -e flag to
exit on any command error. The return code from that script is checked and a
message is written to syslog and /var/log/utah-install to make clear that a
success command failure has been detected.

I haven't been able to reproduce exactly the same problem as in the bug
description, but I'm going to mark the bug as fix committed since any kind of
problem should be detected assuming that apt-get returns a failure code.

Please reopen if the assumption turns out to be false.