IOWA CITY — A weekend robbery is under investigation.According to an Iowa City police news release, officers were called to First and Muscatine avenues at 7:48 p.m. Saturday for a report of a robbery. Officers met with a man who said he had been approached at Kum & Go, 2303 Muscatine Ave., by a woman claiming she needed help getting into a nearby residence.Police said the man followed the woman to an alley south of the 2200 block of Muscatine Avenue, where he was pepper-sprayed by the woman and then jumped by two men.