product_lot_sequence: Incrementation issues

[grindtildeath]

Module

product_lot_sequence

Describe the bug

When opening the detailed operations of an assigned picking for a product
tracked by serial numbers, Odoo systematically calls _get_next_serial even
if there is not any serial number to generate.
Moreover, the widget allowing to generate the serial numbers will not call
the sequence but only increment the number according to the next serial,
potentially leading to a sequence that is not in sync anymore with the created
serial numbers.

To Reproduce

Affected versions: 15.0, 16.0

Steps to reproduce the behavior:

1. Either use a global sequence or a product specific sequence to generate serial numbers
2. On a reception from the supplier for such a product, opening the detailed operation tab will call _get_next_serial and increment the sequence, leading to multiple issues:
   • Calling assign serial numbers will create new numbers that will create stock.production.lot records without incrementing the sequence accordingly
   • The same numbers could be generated on different receptions if these are not validated as soon as the numbers are generated

Expected behavior
Sequence is only incremented for generated lot/serial numbers.

Additional context
cf #1323 (comment)

[github-actions]

There hasn't been any activity on this issue in the past 6 months, so it has been marked as stale and it will be closed automatically if no further activity occurs in the next 30 days.
If you want this issue to never become stale, please ask a PSC member to apply the "no stale" label.

[grindtildeath]

Can we please keep this issue open? 🙏