Updated for https://github.com/koreader/koreader/pull/4691
Also the assert.is_same() argument order was wrong.
The first argument is expected, the second the real-life result.
Otherwise the error message in case of failure is misleading.
I'm afraid this unit test is not maintainable, each time we
change the structure of the defaults.lua we must change this spec
accordingly. We probably will get rid of defaults.lua as well as the
filemanagersetdefaults and this spec.
