So we have a sanity check for the udev monitor fd. Theoretically, it
could happen that the udev monitor fd changes (due to our own wrongdoing,
hence the 'sanity' here) and if that happens it means we are handling an
event from a different entity than we think, thus we should remove the
handle if someone somewhere somehow hits this hypothetical case.
Signed-off-by: NErik Skultety <eskultet@redhat.com>