Register as_<vendor>

gistfile1.diff

diff --git a/django/contrib/gis/db/backends/postgis/operations.py b/django/contrib/gis/db/backends/postgis/operations.py
index 690194f..2a7e1f6 100644
--- a/django/contrib/gis/db/backends/postgis/operations.py
+++ b/django/contrib/gis/db/backends/postgis/operations.py
@@ -4,6 +4,7 @@ from django.conf import settings
 from django.contrib.gis.db.backends.base import BaseSpatialOperations
 from django.contrib.gis.db.backends.postgis.adapter import PostGISAdapter
 from django.contrib.gis.db.backends.utils import SpatialOperator
+from django.contrib.gis.db.models.sql import aggregates # .sql should disappear with 14030
 from django.contrib.gis.geometry.backend import Geometry
 from django.contrib.gis.measure import Distance
 from django.core.exceptions import ImproperlyConfigured
@@ -43,6 +44,12 @@ class PostGISDistanceOperator(PostGISOperator):
         return super(PostGISDistanceOperator, self).as_sql(connection, lookup, template_params, sql_params)
 
 
+class PostGISMakeLine(object):
+    def as_postgresql(self, qn, connection):
+        # Here custom behaviour
+        return super(PostGISMakeLine, self).as_sql(qn, connection)
+
+
 class PostGISOperations(DatabaseOperations, BaseSpatialOperations):
     compiler_module = 'django.contrib.gis.db.models.sql.compiler'
     name = 'postgis'
@@ -87,9 +94,17 @@ class PostGISOperations(DatabaseOperations, BaseSpatialOperations):
         'distance_lt': PostGISDistanceOperator(func='ST_Distance', op='<', geography=True),
         'distance_lte': PostGISDistanceOperator(func='ST_Distance', op='<=', geography=True),
     }
+    gis_aggregates = {
+        'MakeLine': PostGISMakeLine,
+    }
 
     def __init__(self, connection):
         super(PostGISOperations, self).__init__(connection)
+        # register aggregates Mixins (will have to be moved to Base)
+        for klass_name, mixin in self.gis_aggregates.items():
+            base = getattr(aggregates, klass_name)
+            if mixin not in base.__bases__:
+                base.__bases__ = (mixin,) + base.__bases__
 
         prefix = self.geom_func_prefix