Investigate failing functional test

[dogancanbakir]

          lgtm!

$ go run . -u http://testphp.vulnweb.com -ef css,php -j

Follow ups tasks:

• Check if there is any other filtering functionality that is affected by the same behavior of filtering in the output, but still performing requests
• Investigate failing functional tests (probably just running again would be successful)

Originally posted by @Mzack9999 in #1203 (review)