Multiple reviews of whether FBI agents’ political bias affected the Russia-Trump collusion case remain in their infancy, but investigators already have unearthed troubling internal communications long withheld from public view. We already know from FBI counterintelligence agent Peter Strzok’s now-infamous text messages with his fellow agent and reported lover, Lisa Page, that Strzok — the man driving that Russia collusion investigation — disdained Donald Trump and expressed willingness to use his law enforcement powers to “stop” the Republican from becoming president. The question that lingers, unanswered: Did those sentiments affect official actions? Memos the FBI is now producing to the...