tmp.py

from orders.constants import ORDER_STATUS_PLACED
sarahs = Vendor.objects.get(pk=38872)

ols = OrderLine.objects.filter(
        order__order_status__lt=ORDER_STATUS_PLACED,
        product__code__startswith='BB'
)

interesting = []
for ol in ols:
    if sarahs in ol.product.piece.vendors:
        interesting.append(ol)