BOGOTA - Colombia's second-longest oil pipeline was bombed over the weekend, most likely by leftist rebels, a source at state-run Ecopetrol said on Thursday.It was at least the fourth attack since late February on the 780-kilometer Cano Limon-Covenas line, which has a capacity of 220,000 barrels per day, but usually pumps about 80,000."Right now repairs are being prepared for the pipeline," the source said.The attack happened on July 9, the source added.