Never use the expression "if obj" whenever obj is not a simple type.

bt5/erp5_credential/SkinTemplateItem/portal_skins/erp5_credential/CredentialRequest_checkLoginAvailability.xml

@@ -75,7 +75,7 @@ context = getRealContext()\n
 #Allow reference for person in relation with the credential request\n
 if context.getPortalType() == "Credential Request":\n
   related_person = context.getDestinationDecisionValue(portal_type="Person")\n
-  if related_person:\n
+  if related_person is not None:\n
     if related_person.getReference() == value:\n
       return True\n
 \n

bt5/erp5_credential/bt/revision

-358
\ No newline at end of file
+359
\ No newline at end of file