[IMP] column management in project / crm

- Task: https://www.odoo.com/web#id=8545&view_type=form&model=project.task&menu_id=3942&action=327
- Pad: https://pad.odoo.com/p/r.PJlXkLVOd4QZaxGR
Don't understand this code. It seems you will create two columns when only one is necessary.