Stock Picking Update Date

This module modifies the Picking object so that the "Scheduled Time" field is replaced by a similar one that can be modified. If that is done, the scheduled dates of the Moves in the Picking will be updated to get the same value.

As for the original field, if the moves have different scheduled dates, the oldest one is taken.

The same modification is done in incoming, internal and outcoming pickings.

Two existing fields min_date and max_date are left unchanged, because they are used in the core stock module when a picking is moved on the calendar view.