Capture the errcode returned, but don't do anything for now. It's
probably likely that yummain will always fail according to it
because our instroot won't have everything in place that scriplets
need to run. But scriptlets are supposed to always exit with
success, so I dunno.
sort() is inplace for lists, so it doesn't return the sorted list.
Make sure to strip each line read from the packages* files. In the
installPackages() function, concat the packages list on to the
arglist because that's what yummain is expecting.
We get a file descriptor as returned by os.open() when calling
tempfile.mkstemp(), so we need to pass that value to os.fdopen()
before we can write text to it (easily, anyway).
