Shanghai (AFP) – The United States on Saturday warned of “arbitrary” Covid-19 measures in China and said it would let some staff leave its Shanghai consulate amid a surge of infections in the locked-down megacity. Until March, China had kept cases low with snap lockdowns, mass testing and travel restrictions, but more than 100,000 cases have been reported in Shanghai since March in a test of the country’s strict zero-Covid policy. The city’s roughly 25 million inhabitants were locked down in phases last week, prompting complaints of food shortages and viral videos of disgruntled residents scuf…