Remove `except` block which immediately raises the same exception again (it's
not a subclass of another caught exception, so this is safe).
Remove a false positive, because it is not emitted from the code base.
Disable subprocess-popen-preexec-fn in startProgram, which is not used
internally.
Fix up 2to3 complaints. I've decided to do with wrapping list
comprehension inside list() to get the generators to run in several
places instead of list(map( or list(filter( which seem less readable to
me.
