[bfss] Catch EnvironmentError instead of OSError when trying to read attributes bffstored This will also catch IOError (as file not found) that might be encountered expectable too.

if versions_map['cubicweb'][0] == (3, 7, 4):
    config['http-session-time'] *= 60
    config['cleanup-session-time'] *= 60
    config['cleanup-anonymous-session-time'] *= 60