Fixed #19069 -- Improved the error message when trying to query a swapped model.

Thanks to Preston Holmes for the suggestion.

tests/regressiontests/managers_regress/models.py

@@ -10,14 +10,17 @@ class OnlyFred(models.Manager):
     def get_query_set(self):
         return super(OnlyFred, self).get_query_set().filter(name='fred')
 
+
 class OnlyBarney(models.Manager):
     def get_query_set(self):
         return super(OnlyBarney, self).get_query_set().filter(name='barney')
 
+
 class Value42(models.Manager):
     def get_query_set(self):
         return super(Value42, self).get_query_set().filter(value=42)
 
+
 class AbstractBase1(models.Model):
     name = models.CharField(max_length=50)
 
@@ -29,6 +32,7 @@ class AbstractBase1(models.Model):
     manager2 = OnlyBarney()
     objects = models.Manager()
 
+
 class AbstractBase2(models.Model):
     value = models.IntegerField()
 
@@ -38,6 +42,7 @@ class AbstractBase2(models.Model):
     # Custom manager
     restricted = Value42()
 
+
 # No custom manager on this class to make sure the default case doesn't break.
 class AbstractBase3(models.Model):
     comment = models.CharField(max_length=50)
@@ -45,6 +50,7 @@ class AbstractBase3(models.Model):
     class Meta:
         abstract = True
 
+
 @python_2_unicode_compatible
 class Parent(models.Model):
     name = models.CharField(max_length=50)
@@ -54,6 +60,7 @@ class Parent(models.Model):
     def __str__(self):
         return self.name
 
+
 # Managers from base classes are inherited and, if no manager is specified
 # *and* the parent has a manager specified, the first one (in the MRO) will
 # become the default.
@@ -64,6 +71,7 @@ class Child1(AbstractBase1):
     def __str__(self):
         return self.data
 
+
 @python_2_unicode_compatible
 class Child2(AbstractBase1, AbstractBase2):
     data = models.CharField(max_length=25)
@@ -71,6 +79,7 @@ class Child2(AbstractBase1, AbstractBase2):
     def __str__(self):
         return self.data
 
+
 @python_2_unicode_compatible
 class Child3(AbstractBase1, AbstractBase3):
     data = models.CharField(max_length=25)
@@ -78,6 +87,7 @@ class Child3(AbstractBase1, AbstractBase3):
     def __str__(self):
         return self.data
 
+
 @python_2_unicode_compatible
 class Child4(AbstractBase1):
     data = models.CharField(max_length=25)
@@ -89,6 +99,7 @@ class Child4(AbstractBase1):
     def __str__(self):
         return self.data
 
+
 @python_2_unicode_compatible
 class Child5(AbstractBase3):
     name = models.CharField(max_length=25)
@@ -99,10 +110,12 @@ class Child5(AbstractBase3):
     def __str__(self):
         return self.name
 
+
 # Will inherit managers from AbstractBase1, but not Child4.
 class Child6(Child4):
     value = models.IntegerField()
 
+
 # Will not inherit default manager from parent.
 class Child7(Parent):
     pass