Bug
===
If we create a selection properties with some options, change the type
to char, and then again to selection, the options are restored.
But, if we just change the type to char, the options of the old
property are stored in the database, and we don't want that.
Task-3346103
closesodoo/odoo#124129
X-original-commit: 35c99a9110cec3317f36d4ddffae5196b58939e5
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>