In 11.0 f8b38f64d improved the column group by managment when reloading
several times by having the same "groupbys" dictionaries between the
pivot model instance and the header menu.
This has been reverted in 12.0 (with c6e7adfb95) because the following
pivot tests failed with the change:
- 'rendering of pivot view with comparison'
- 'export data in excel with comparison'
The failure is because now that the "groupbys" dictionaries are the same
object, the truncated dictionary of a header truncate the one of the
model instance.
So if we search something that has no results, then something with
results, the groupbys could be lost.
This behavior has no reason to be and is changed in 11.0 with #31644,
this commit is the forward-port of f8b38f64d and #31644.
closes#31627
Signed-off-by: Nicolas Lempereur (nle) <nle@odoo.com>
Nicolas Lempereur
b8d4fe6d38