attrs strange behavior in editable one2many

Webclient 6.0 revno 4912

A test module (named attrs_bug) is provided to easily reproduce the bug.

With this king of view:

                        <tree editable="top">
                            <field name="float1" attrs="{'readonly': [('float1_required', '=', 0)], 'required': [('float1_required', '=', 1)]}"/>
                            <field name="float2" attrs="{'readonly': [('float2_required', '=', 0)], 'required': [('float2_required', '=', 1)]}"/>
                            <field name="float1_required"/>
                            <field name="float2_required"/>
                        </tree>

you observe strange behaviors when you check and uncheck float1_required and float2_required:

If you create a new line, float1 and 2 will be readonly (which is ok since both required fields are unchecked).
If you check required1, nothing happens, if you then check required2, float1 (!!) becomes required !

You can continue playing with the check box and quickly figure that something is wrong with attrs...