Error with drag and drop to reorder on category tree view.
Following discussion started on https://discuss.tryton.org/t/reorganization-of-the-sales-line-bug-in-gtk-client/
Python 3.5.3
tryton 5.1.0
On a category tree view, dragging and dropping throws an error.
ERROR:tryton.common.common: File "tryton/tryton/gui/window/view_form/view/list.py", line 776, in drag_data_received
data = json.loads(selection_data)
File "/usr/lib/python3.5/json/__init__.py", line 312, in loads
s.__class__.__name__))
the JSON object must be str, not 'bytes'