Sounds like a good idea...  at the same time add uom d'achat by supplier SVP

When an active field will be added to product supplier, it should also follow the issue4347.

Shouldn't it be a easy as putting a ('active', '=', 'true') clause in the search domain?

not quite, the product (still activated) is the right product from the right supplier, but the initial erroneously entered product with the wrong uom (which is deactivated) still shows up... 
giving two [identical except for uom] selections where there should only be one.

With respect to the template, it's not the [real] product (it's merely a template) so I don't understand how it could affect the workflow discussed, outside of where probably there is a product [template] form that will de-activate all products variants when de-activating the template.

OK, I think I understand what you try to say. You are selecting a product supplier for a deactivate product. So yes there is no mechanism to deactivate also the product supplier but it is not a bug but a new feature.

well, I tried disactivating both the template and the product, no change.

I'm pretty sure it is a duplicate of issue4347.
Re-open it if not.

we have a number of products where previously the uom was entered as Unit but later needed to be different (like liter) so the product was duplicated, the uom corrected in the new and the old dis-activated.
But in the purchase form using the suppliers product, both active and dis-activated products are displayed during entry completion which is quite perturbing (especially since the names are probably the same)

In demo5.0 I created the products 'Foo bared' (initial and now dis-activated) as well as 'Foo' (rectified).

It should not be possible to create new purchases with dis-activated products.