New projects gather unassigned dish ingredients

coocook_dbck.pl has been reporting unassigned dish ingredients for projects with purchase lists on Coocook.org for some weeks now.

• Research

Steps to reproduce:

1. create project
2. create meal
3. create dish
4. add a dish ingredient
5. create purchase list→has item
6. try to delete ingredient from dish→IngredientsEditor hides ingredients
7. reload page
8. dish ingredient visible again→ingredient still exists but not assigned to purchase list anymore