models.py

from django.db import models


class Orange(models.Model):
    pass


class BaseClass(models.Model):
    field = models.ForeignKey(Orange)
    class Meta:
        abstract = True


class Parent1(BaseClass):
    class Meta:
        abstract=True


class Parent2(BaseClass):
    class Meta:
        abstract=True


class Child(Parent1, Parent2):
    pass

multiple_abstract_inheritance_r15458.diff

diff --git a/django/db/models/fields/__init__.py b/django/db/models/fields/__init__.py
index fd0a295..6bfdefe 100644
--- a/django/db/models/fields/__init__.py
+++ b/django/db/models/fields/__init__.py
@@ -234,6 +234,10 @@ class Field(object):
     def contribute_to_class(self, cls, name):
         self.set_attributes_from_name(name)
         self.model = cls
+        if not hasattr(self, "_declared_on_class"):
+            self._declared_on_class = cls
+        if not hasattr(self, "_first_concrete_class") and not cls._meta.abstract:
+            self._first_concrete_class = cls
         cls._meta.add_field(self)
         if self.choices:
             setattr(cls, 'get_%s_display' % self.name, curry(cls._get_FIELD_display, field=self))
diff --git a/django/db/models/options.py b/django/db/models/options.py
index 2f64c56..e6f286d 100644
--- a/django/db/models/options.py
+++ b/django/db/models/options.py
@@ -152,7 +152,16 @@ class Options(object):
         # Insert the given field in the order in which it was created, using
         # the "creation_counter" attribute of the field.
         # Move many-to-many related fields from self.fields into
-        # self.many_to_many.
+        # self.many_to_many. Ignore duplicate fields inherited from a
+        # single abstract base class.
+        try:
+            f = self.get_field(field.name)
+        except FieldDoesNotExist:
+            pass
+        else:
+            if f._declared_on_class == field._declared_on_class and getattr(f, '_first_concrete_class', None) == getattr(field, '_first_concrete_class', None):
+                return
+
         if field.rel and isinstance(field.rel, ManyToManyRel):
             self.local_many_to_many.insert(bisect(self.local_many_to_many, field), field)
             if hasattr(self, '_m2m_cache'):

traceback1.sh

Unhandled exception in thread started by <bound method Command.inner_run of <django.core.management.commands.runserver.Command object at 0x101470490>>
Traceback (most recent call last):
  File "..../django/core/management/commands/runserver.py", line 88, in inner_run
    self.validate(display_num_errors=True)
  File "..../django/core/management/base.py", line 253, in validate
    raise CommandError("One or more models did not validate:\n%s" % error_text)
django.core.management.base.CommandError: One or more models did not validate:
app.child: Accessor for field 'field' clashes with related field 'Orange.child_set'. Add a related_name argument to the definition for 'field'.
app.child: Accessor for field 'field' clashes with related field 'Orange.child_set'. Add a related_name argument to the definition for 'field'.

traceback2.sh

Unhandled exception in thread started by <bound method Command.inner_run of <django.core.management.commands.runserver.Command object at 0x10146e4d0>>
Traceback (most recent call last):
  File "..../django/core/management/commands/runserver.py", line 88, in inner_run
    self.validate(display_num_errors=True)
  File "..../django/core/management/base.py", line 253, in validate
    raise CommandError("One or more models did not validate:\n%s" % error_text)
django.core.management.base.CommandError: One or more models did not validate:
app.child: Accessor for field 'field' clashes with related field 'Orange.app_child_related'. Add a related_name argument to the definition for 'field'.
app.child: Reverse query name for field 'field' clashes with related field 'Orange.app_child_related'. Add a related_name argument to the definition for 'field'.
app.child: Accessor for field 'field' clashes with related field 'Orange.app_child_related'. Add a related_name argument to the definition for 'field'.
app.child: Reverse query name for field 'field' clashes with related field 'Orange.app_child_related'. Add a related_name argument to the definition for 'field'.