BRUSSELS (Reuters) - The European Union’s executive has not been forewarned about a possible U.S. withdrawal from the global deal on fighting climate change, a spokeswoman said on Wednesday.  President Donald Trump will follow through on a campaign pledge to pull the United States out of a pact, a source briefed on the decision told Reuters, a move that promises to deepen a rift with U.S. allies. The executive European Commission said separately on Wednesday the 28-nation bloc was ready to take on global leadership should the United States pull out. 