#4 exit code does not reflect error status

[Anonymous]

When building an RPM using crust, one of the files had a space
in its name. This tickled a bug somewhere, causing rpm to fail to
build the rpm. That is a know but in crust. The new issue is that
when crust exited the exit value was 0, indicating success.

If the rpm fails to build crust should exit with a non-zero exit value.