In a rare mea culpa from Wall Street, analysts from Goldman Sachs this morning upgraded Microsoft stock from “sell” to “neutral” — acknowledging that they “failed to appreciate” that the Redmond company’s share price would defy lower earnings expectations thanks to promising signs in the company’s cloud computing business. “We were wrong,” wrote Goldman Sachs analyst Heather Bellini and her colleagues in the note to clients this morning, entitled, “Righting a Wrong.” Here’s an excerpt from the report. We upgrade MSFT to Neutral from Sell. Since its addition to the Sell list on 4/11/2013, MSFT is +84% vs. the S&P +29%. Despite out year estimates consistently compressing, we failed to appreciate…...