import mellon only if in INSTALLED_APPS (#14474)

combo/apps/lingo/views.py

@@ -40,9 +40,9 @@ import eopayment
 
 from combo.utils import check_request_signature, aes_hex_decrypt, DecryptionError
 
-try:
+if 'mellon' in settings.INSTALLED_APPS:
     from mellon.models import UserSAMLIdentifier
-except ImportError:
+else:
     UserSAMLIdentifier = None
 
 from .models import (Regie, BasketItem, Transaction, TransactionOperation,

combo/public/views.py

@@ -38,9 +38,9 @@ else:
 from django.utils.translation import ugettext as _
 from django.forms.widgets import Media
 
-try:
+if 'mellon' in settings.INSTALLED_APPS:
     from mellon.utils import get_idps
-except ImportError:
+else:
     get_idps = lambda: []
 
 from combo.data.models import CellBase, Page, ParentContentCell, TextCell