Pyflakes fixes.

__init__.py

@@ -1,11 +1,10 @@
 #The COPYRIGHT file at the top level of this repository contains the full
 #copyright notices and license terms.
 from trytond.pool import Pool
-from .invoice import *
-
+from . import invoice
 
 def register():
     Pool.register(
-        Sale,
-        Invoice,
+        invoice.Sale,
+        invoice.Invoice,
         module='account_invoice_shop', type_='model')

invoice.py

@@ -7,8 +7,6 @@ from trytond.transaction import Transaction
 from trytond.pool import Pool, PoolMeta
 from trytond.pyson import Eval
 
-__all__ = ['Sale', 'Invoice']
-
 
 class Sale(metaclass=PoolMeta):
     __name__ = 'sale.sale'

tests/__init__.py

@@ -1,4 +1,5 @@
 # The COPYRIGHT file at the top level of this repository contains the full
 # copyright notices and license terms.
-
 from .test_account_invoice_shop import suite
+
+__all__ = ['suite']