cubicweb #3179561 [py3k] kill future compat warnings [done]

prioritynormal
typeenhancement
done in<not specified>
load0.500
load left0.000
closed by#0814b9dd9bf3 [py3k] note about future warning on __eq__ vs __hash__
patch[py3k] kill future warning about __eq__ vs __hash__ [applied][formfields] py3k kill future compat warning [applied]