[1.6.x] Fixed #23265 -- Used system-specific encoding in runserver

Thanks SpaceFox for the report.
Backport of 055d95fce0 from master.

django/core/management/commands/runserver.py

@@ -11,6 +11,7 @@ import socket
 from django.core.management.base import BaseCommand, CommandError
 from django.core.servers.basehttp import run, get_internal_wsgi_application
 from django.utils import autoreload
+from django.utils.encoding import get_system_encoding
 from django.utils import six
 
 naiveip_re = re.compile(r"""^(?:
@@ -101,7 +102,7 @@ class Command(BaseCommand):
         self.validate(display_num_errors=True)
         now = datetime.now().strftime('%B %d, %Y - %X')
         if six.PY2:
-            now = now.decode('utf-8')
+            now = now.decode(get_system_encoding())
 
         self.stdout.write((
             "%(started_at)s\n"

docs/releases/1.6.6.txt

@@ -33,3 +33,6 @@ Bugfixes
 
 * Restored bug fix for sending unicode email with Python 2.6.5 and below
   (`#19107 <https://code.djangoproject.com/ticket/19107>`_).
+
+* Prevented ``UnicodeDecodeError`` in ``runserver`` with non-UTF-8 and
+  non-English locale (`#23265 <https://code.djangoproject.com/ticket/23265>`_).