[1.11.x] Fixed #27966 -- Bumped required psycopg2 version to 2.5.4.

Thanks Tim Graham for the review.

Backport of 43380e9110 from master

django/db/backends/postgresql/base.py

@@ -32,8 +32,8 @@ def psycopg2_version():
 
 PSYCOPG2_VERSION = psycopg2_version()
 
-if PSYCOPG2_VERSION < (2, 4, 5):
-    raise ImproperlyConfigured("psycopg2_version 2.4.5 or newer is required; you have %s" % psycopg2.__version__)
+if PSYCOPG2_VERSION < (2, 5, 4):
+    raise ImproperlyConfigured("psycopg2_version 2.5.4 or newer is required; you have %s" % psycopg2.__version__)
 
 
 # Some of these import psycopg2, so import them after checking if it's installed.

docs/ref/contrib/postgres/fields.txt

@@ -517,7 +517,7 @@ using in conjunction with lookups on
     of the JSON which allows indexing. The trade-off is a small additional cost
     on writing to the ``jsonb`` field. ``JSONField`` uses ``jsonb``.
 
-    **As a result, this field requires PostgreSQL ≥ 9.4 and Psycopg2 ≥ 2.5.4**.
+    **As a result, this field requires PostgreSQL ≥ 9.4**.
 
 Querying ``JSONField``
 ----------------------

docs/ref/contrib/postgres/index.txt

@@ -9,9 +9,6 @@ PostgreSQL has a number of features which are not shared by the other databases
 Django supports. This optional module contains model fields and form fields for
 a number of PostgreSQL specific data types.
 
-Psycopg2 2.5 or higher is required, though we highly recommend using the latest
-release. Some fields require higher versions.
-
 .. note::
     Django is, and will continue to be, a database-agnostic web framework. We
     would encourage those writing reusable applications for the Django

docs/ref/databases.txt

@@ -92,8 +92,8 @@ below for information on how to set up your database correctly.
 PostgreSQL notes
 ================
 
-Django supports PostgreSQL 9.3 and higher. It requires the use of `psycopg2`_
-2.4.5 or higher (or 2.5+ if you want to use :mod:`django.contrib.postgres`).
+Django supports PostgreSQL 9.3 and higher. `psycopg2`_ 2.5.4 or higher is
+required, though the latest release is recommended.
 
 .. _psycopg2: http://initd.org/psycopg/
 

docs/releases/1.11.txt

@@ -521,6 +521,9 @@ Django 1.11 sets PostgreSQL 9.3 as the minimum version it officially supports.
 Support for PostGIS 2.0 is also removed as PostgreSQL 9.2 is the last version
 to support it.
 
+Also, the minimum supported version of psycopg2 is increased from 2.4.5 to
+2.5.4.
+
 ``LiveServerTestCase`` binds to port zero
 -----------------------------------------
 

tests/requirements/postgres.txt

@@ -1 +1 @@
-psycopg2>=2.5
+psycopg2>=2.5.4