The Senate voted Thursday in Sacramento to override Gov. Pete Wilson's veto of a politically charged illegal immigrant bill, but Republicans blocked an effort to complete the override in the Assembly. It was the first time since 1984 that either house of the Legislature had voted to overturn a veto. The Legislature hasn't overridden a veto since 1979. The vetoed bill, by Sen. Art Torres, D-Los Angeles, would have directed state officials to try to transfer about 16,000 illegal immigrants in California prisons to federal custody to reduce state costs.