Much has been made of Sarah Palin’s mesmerizing and bewildering endorsement of Donald Trump last week — her trademark syntax, her made-up words, her stamina. Equally fascinating ­— and distracting — was the unusual spangly top Palin wore for the occasion. What do you call that thing? Palin, it turns out, was sporting a bolero jacket, similar to a shrug, but more formal and made of stiffer material. Fashion history tells us that the bolero was inspired by the chaquetilla, a short, rigid jacket, worn by Spanish matadors. Palin’s bolero included silver, red, gold, and blue stripes made of beads (according to People magazine, it retails for just under $700). On “Saturday Night Live’’ a few days later, Tina Fey re-created the Palin bolero to great effect.