`cassette.filter_request` only filters some request attributes like
headers but does not take into account any of the `match_on`
configurations. As a result if a similar request has been seen before
but does not fully match as per `match_on`, writes will be disallowed.
`cassette.__contains__` however fully takes into account all `match_on`
matchers and therefore will only guard against recording to the cassette
when the same request has been previously recorded

assuming:

* any of the ignore requests is configured as documented in
  https://vcrpy.readthedocs.io/en/latest/advanced.html?highlight=ignore_hosts#ignore-requests

* request matchers are configured as documented in
  https://vcrpy.readthedocs.io/en/latest/configuration.html#request-matching

since the filtering logic returns None when request should be ignored
however matchers assume both requests being compared are valid
requests and so when one of the requests is None
it raises AttributeError as no attribute such as "uri"
can be accessed on NoneType

this fix simply does not consider the request for matching
if it is ignored