LONDON (Reuters) - Prime Minister Boris Johnson is pushing ahead with legislation that will deliberately breach the European Union exit treaty signed in January, despite warnings that it could wreck trade deals with the EU and the United States.The success or failure of last-gasp Brexit talks in coming days will determine whether Johnson has to face those consequences, or if the most troublesome parts of the bill can be quietly abandoned.The Internal Market Bill is aimed at ensuring the United Kingdom’s four nations can trade freely with one another after leaving the EU. But the government says that requires creating powers to override part of the Withdrawal Treaty - a breach of international law it says is necessary to create a safety net that protects Northern Ireland if Brexit talks fail.The part of the legislation that creates these powers was stripped from the bill by parliament’s upper chamber on Nov. 9.