Newton officials are calling their refusal to allow FBI agents access to library computers without a warrant during a terrorist threat last week “their finest hour.” Law enforcement officials say it’s a “nightmare.” Police rushed to the Newton Free Library after tracing a terrorist threat e-mailed to Brandeis University to a computer at the library. But requests to examine computers Jan. 18 were rebuffed by Newton library Director Kathy Glick-Weil and Mayor David Cohen on the grounds that they did not have a warrant. Cohen, defending the library’s actions, called the legal standoff one of Newton’s “finest hours.” “We showed...