Remove some more references to objects holding (possibly indirectly)
reference to libvirt connection:
- local variables in tearDown function
- running Admin API calls (especially admin.Events)
- vmm._libvirt_conn directly, in case some reference to Qubes()
is still there
- any instance attribute that is an object from 'qubes' python package
(instead of just those descending from BaseVM)
- do not create new Qubes() instance for removing VMs - if we already
have one in self.app
Then trigger garbage collector to really cleanup those objects (and
close relevant file descriptors). It's important do do this before
closing event loop, because some of descructors may try to use it (for
example remove registered handlers).
c53582b285