Server validation of "required" attribute on xxx2many fields
xxx2many fields that are marked as required (either directly or with 'states'
attribute, are not always properly checked.
More precisely, the follwing line (1074) seem it is not correct because it does
not check for empty lists:
if required and record[field_name] is None:
I tried to replace it by:
if required and (record[field_name] is None or
record[field_name] == []):
But didn't work (did not even install modules). Need to investigate it further.