By Sheila Dang and Nivedita Balu (Reuters) -Twitter Inc on Friday blamed its ongoing battle to close its $44-billion acquisition by Elon Musk and a weakening digital advertising market for a surprise fall in quarterly revenue and a net loss. The results come as Twitter has sued Musk for dropping his offer to buy the company, and is now preparing for a legal showdown in a trial set to begin in October. The deal uncertainty has worried Twitter’s advertisers and caused chaos inside the company. Advertising revenue rose just 2% to $1.08 billion, missing Wall Street expectations of $1.22 billion, a…