filter_post_data_parameters doesn't filter out parameters with non-ASCII chars

[ubalklen]

import requests
import vcr

url = "http://www.iana.org/domains/reserved"

# Password will be visible in the cassette
with vcr.use_cassette("bugged_vcr.yaml", filter_post_data_parameters=["api:key"]):
    requests.post(url, data={"api:key": "SuperSecretP@ssword"})

# Works if I preemptively do the percentage encoding myself
with vcr.use_cassette("ok_vcr.yaml", filter_post_data_parameters=["api%3Akey"]):
    requests.post(url, data={"api:key": "SuperSecretP@ssword"})