This test case illustrates the problem with sku matching.

There is a gap between the diff result and the variants array of a product.
We have to find another way to get the corresponding variant for the diff entry.
Finally found a way to compare variants based on SKU.

We store in the diff model the original array index of each side (old and new).
On building the actions we can use those indexes to access the right variant of the
corresponding objects.
Add new tests specific for sku matching.
Format arrays.
More tests for sku matching.
Build all branches.