Spike Lee’s 2018 movie comes to HBO tonight, starring John David Washington in the true but improbable tale of police officer Ron Stallworth, who in the 1970s went undercover and infiltrated the Ku Klux Klan. How? With lots of help from Flip Zimmerman (Adam Driver), a fellow officer who became the white face to Stallworth’s disembodied phone voice. And somehow, it worked…