Last Thursday, workers put up a long wall of plywood where the bottom half of the besieged Shepard Fairey mural on E. Houston St. once was. Vandals had destroyed the mural’s lower part, leaving it hanging in tatters. Soon after the plywood fence was put up, however, someone promptly drew a 50-foot-long penis on it. As of Tuesday afternoon, the phallus had been half covered over with black paint.