IBM’s board was staring down difficult news: The second quarter had been a bust. Directors had long known that the artificial-intelligence revolution would upend the technology icon’s business, but the pain came sooner than expected, leaving the company with a tough choice, according to people familiar with the discussions. Board members debated whether to issue a rare warning that bad news was coming or wait for the numbers to hit the tape a week later when executives could discuss them with investors, the people said.  After asking tough questions of CEO Arvind Krishna , the board agreed to take its…