Survey comment field text validation is wrong

[Prakash Pandey]

If a comment field has a length based validation, it works if a string value exists for the field. however, if the comment field is left blank, the validation does not work.

This is because of the poor logic in create method [1].

The condition in [1] already kicks in condition [2] is never evaluated.

[1] https://github.com/akretion/openerp-addons/blob/318685c447ab88144e00d903cc5e72448708cd96/survey/wizard/survey_answer.py#L676
[2] https://github.com/akretion/openerp-addons/blob/318685c447ab88144e00d903cc5e72448708cd96/survey/wizard/survey_answer.py#L681