HAVERHILL — A Massachusetts man who left another man with broken bones in an unprovoked attack is heading to state prison.The Eagle-Tribune reports that a judge sentenced 48-year-old Shane Mambro to a minimum of two years in prison after the Haverhill man pleaded guilty to assault and battery causing serious bodily injury.Police say Mambro had been arguing with his girlfriend outside of a bar in October 2016 when he crossed the street and beat a man walking alone for no reason.