This commit's purpose is to allow the user to remove the planned date
end, or the planned date start of a project from the list view, or the form
view of the project. If the user removes either the planned date end, or
the planned date start, both dates will be removed. If the user tries to
add only a date end or a date start while keeping the other date empty
on a project with no planned date, these changes will be discarded.
The goal of this fix is for the projects to always have either both dates
set, or both dates set to False.
closesodoo/odoo#130651
X-original-commit: 250a0d233c8c2e074b967d59d53b1d4aac5feba2
Related: odoo/enterprise#45131
Signed-off-by: Xavier Bol (xbo) <xbo@odoo.com>