It had nothing to do with the jacket, though. I suspect the jacket obscures a bulletproof vest on presidential candidates in public. She may have ditched the vest later if the scene outside the apartment building was deemed secure enough to take that chance.
That scene outside the apartment building was deemed SO secure that you had an absolutely clear, um, “view” of her from at least fifty feet up the sidewalk.
https://twitter.com/ABCLiz/status/774999166489690113