wizard hangs after cancelling it, avoiding clean termination

steps to reproduce:

1. enter wizard
2. make checks fail (no https here, might be other)
3. hit ctrl-c (or cancel in first-run, I guess it should behave the same)
4. It hangs. Expected: clean exit.

(from redmine: created on 2013-07-01, closed on 2013-07-08, duplicates #2939 (closed))