MSNBC’s Joe Scarborough warned that Donald Trump was in more danger in the Republican presidential primary than he might realize. The former president easily beat challenger Nikki Haley once again, this time in Michigan, but his former U.N. ambassador intends to remain in the race until the March 5 “Super Tuesday” primary, and the “Morning Joe” host said there were clear “warning signs” in Tuesday’s GOP primary results. “This is simple, it’s open primaries versus closed primaries, and we’ve been saying all along this election is going to be won not across the fruited plains of America, it’s go…