Fixed #23107 -- Made runserver output respect --no-color.

This commit reverts 67d7da5fb9.

The previous fix changed the environment globally, which meant
that any call to `call_command(no_color=True)` prevented further
`call_command` with color.

This fix still relies on the environment because it's currently the only
way to reach WSGIRequestHandler, but it's now limited to the `runserver`
command. This seems an acceptable compromise considering `runserver` runs
indefinitely.

Thanks Tim Graham for the review.

django/core/management/base.py

@@ -386,7 +386,6 @@ class BaseCommand(object):
         if options.get('no_color'):
             self.style = no_style()
             self.stderr = OutputWrapper(options.get('stderr', sys.stderr))
-            os.environ[str("DJANGO_COLORS")] = str("nocolor")
         else:
             self.stderr = OutputWrapper(options.get('stderr', sys.stderr), self.style.ERROR)
 

django/core/management/commands/runserver.py

@@ -41,6 +41,14 @@ class Command(BaseCommand):
         parser.add_argument('--noreload', action='store_false', dest='use_reloader', default=True,
             help='Tells Django to NOT use the auto-reloader.')
 
+    def execute(self, *args, **options):
+        if options.get('no_color'):
+            # We rely on the environment because it's currently the only
+            # way to reach WSGIRequestHandler. This seems an acceptable
+            # compromise considering `runserver` runs indefinitely.
+            os.environ[str("DJANGO_COLORS")] = str("nocolor")
+        super(Command, self).execute(*args, **options)
+
     def get_handler(self, *args, **options):
         """
         Returns the default WSGI handler for the runner.

tests/admin_scripts/tests.py

@@ -1397,7 +1397,6 @@ class CommandTypes(AdminScriptTestCase):
         out = StringIO()
 
         call_command('color_command', no_color=True, stdout=out)
-        self.assertEqual(os.environ.get('DJANGO_COLORS', ''), 'nocolor')
         self.assertEqual(out.getvalue(), 'BEGIN\n')
 
     def test_base_command(self):