 still do
our best to clear any remaining zipimport.zipimporter related cached data
that might somehow later get used when attempting to load data from the new
distribution and thus cause such load operations to fail. Note that when
tracking down such remaining stale data, we can not catch every conceivable
usage from here, and we clear only those that we know of and have found to
cause problems if left alive. Any remaining caches should be updated by
whomever is in charge of maintaining them, i.e. they should be ready to
handle us replacing their zip archives with new distributions at runtime.

N)