Added a bulk option to RelatedManager remove() and clear() methods

Refs #21169

docs/ref/models/relations.txt

@@ -110,6 +110,17 @@ Related objects reference
         the ``blog`` :class:`~django.db.models.ForeignKey` doesn't have
         ``null=True``, this is invalid.
 
+        .. versionchanged 1.7::
+
+        For :class:`~django.db.models.ForeignKey` objects, this method accepts
+        a ``bulk`` argument to control how to perform the operation.
+        If ``True`` (the default), ``QuerySet.update()`` is used.
+        If ``bulk=False``, the ``save()`` method of each individual model
+        instance is called instead. This triggers the
+        :data:`~django.db.models.signals.pre_save` and
+        :data:`~django.db.models.signals.post_save` signals and comes at the
+        expense of performance.
+
     .. method:: clear()
 
         Removes all objects from the related object set::
@@ -121,7 +132,8 @@ Related objects reference
         them.
 
         Just like ``remove()``, ``clear()`` is only available on
-        :class:`~django.db.models.ForeignKey`\s where ``null=True``.
+        :class:`~django.db.models.ForeignKey`\s where ``null=True`` and it also
+        accepts the ``bulk`` keyword argument.
 
     .. note::
 

docs/releases/1.7.txt

@@ -430,6 +430,11 @@ Models
 * :class:`F expressions <django.db.models.F>` support the power operator
   (``**``).
 
+* The ``remove()`` and ``clear()`` methods of the related managers created by
+  ``ForeignKey`` and ``GenericForeignKey`` now accept the ``bulk`` keyword
+  argument to control whether or not to perform operations in bulk
+  (i.e. using ``QuerySet.update()``). Defaults to ``True``.
+
 Signals
 ^^^^^^^
 
@@ -589,11 +594,13 @@ Fixing the issues introduced some backward incompatible changes:
 - The default implementation of ``remove()`` for ``ForeignKey`` related managers
   changed from a series of ``Model.save()`` calls to a single
   ``QuerySet.update()`` call. The change means that ``pre_save`` and
-  ``post_save`` signals aren't sent anymore.
+  ``post_save`` signals aren't sent anymore. You can use the ``bulk=False``
+  keyword argument to revert to the previous behavior.
 
 - The ``remove()`` and ``clear()`` methods for ``GenericForeignKey`` related
   managers now perform bulk delete. The ``Model.delete()`` method isn't called
-  on each instance anymore.
+  on each instance anymore. You can use the ``bulk=False`` keyword argument to
+  revert to the previous behavior.
 
 - The ``remove()`` and ``clear()`` methods for ``ManyToManyField`` related
   managers perform nested queries when filtering is involved, which may or