Legendary Boston band Pixies has made headlines recently for dropping another bass player and recruiting Paz Lenchantin for its upcoming tour, which hits The Orpheum in Boston on Jan. 18. Today, however, the band has news that everyone can celebrate, releasing a four-song “EP-2,” available for digital download or limited-edition 10-inch vinyl on the band’s website. That’s not all, though, folks. Those well studied in the band’s history will be excited to hear that one of the tracks, “Greens and Blue,” has been described by Frank Black as the sequel to “Surfer Rosa” classic “Gigantic.” If that’s not good news, I’m not sure what is.