[1.7.x] Fixed #22048 - Enhanced docs to cover nonexistent one-to-one relationships.

Thanks EvilDMP for the suggestion.

Backport of ec08d62a20 from master

docs/ref/models/fields.txt

@@ -1469,6 +1469,15 @@ your resulting ``User`` model will have the following attributes::
     >>> hasattr(user, 'supervisor_of')
     True
 
+A ``DoesNotExist`` exception is raised when accessing the reverse relationship
+if an entry in the related table doesn't exist. For example, if a user doesn't
+have a supervisor designated by ``MySpecialUser``::
+
+    >>> user.supervisor_of
+    Traceback (most recent call last):
+        ...
+    DoesNotExist: User matching query does not exist.
+
 .. _onetoone-arguments:
 
 Additionally, ``OneToOneField`` accepts all of the extra arguments

docs/topics/db/examples/one_to_one.txt

@@ -61,10 +61,17 @@ A Place can access its restaurant, if available::
 
 p2 doesn't have an associated restaurant::
 
+    >>> from django.core.exceptions import ObjectDoesNotExist
+    >>> try:
     >>>     p2.restaurant
-    Traceback (most recent call last):
+    >>> except ObjectDoesNotExist:
-        ...
+    >>>     print("There is no restaurant here.")
-    DoesNotExist: Restaurant matching query does not exist.
+    There is no restaurant here.
+
+You can also use ``hasattr`` to avoid the need for exception catching::
+
+    >>> hasattr(p2, 'restaurant')
+    False
 
 Set the place using assignment notation. Because place is the primary key on
 Restaurant, the save will create a new restaurant::