Remove unneded open(.., 'U') when on python 3.

Universal newlines is enabled by default on py3, and the usage of 'U' is
deprecated in py3.4.

django/core/management/commands/makemessages.py

@@ -13,6 +13,7 @@ from django.core.management.utils import (handle_extensions, find_command,
     popen_wrapper)
 from django.utils.encoding import force_str
 from django.utils.functional import total_ordering
+from django.utils import six
 from django.utils.text import get_text_list
 from django.utils.jslex import prepare_js_for_gettext
 
@@ -93,7 +94,7 @@ class TranslatableFile(object):
             orig_file = os.path.join(self.dirpath, self.file)
             is_templatized = file_ext in command.extensions
             if is_templatized:
-                with open(orig_file, "rU") as fp:
+                with open(orig_file, 'r' if six.PY3 else 'rU') as fp:
                     src_data = fp.read()
                 thefile = '%s.py' % self.file
                 content = templatize(src_data, orig_file[2:])
@@ -440,7 +441,7 @@ class Command(NoArgsCommand):
         for domain in domains:
             django_po = os.path.join(django_dir, 'conf', 'locale', locale, 'LC_MESSAGES', '%s.po' % domain)
             if os.path.exists(django_po):
-                with io.open(django_po, 'rU', encoding='utf-8') as fp:
+                with io.open(django_po, 'r' if six.PY3 else 'rU', encoding='utf-8') as fp:
                     m = plural_forms_re.search(fp.read())
                 if m:
                     plural_form_line = force_str(m.group('value'))

django/core/management/sql.py

@@ -9,6 +9,7 @@ from django.apps import apps
 from django.conf import settings
 from django.core.management.base import CommandError
 from django.db import models, router
+from django.utils import six
 
 
 def sql_create(app_config, style, connection):
@@ -198,7 +199,7 @@ def custom_sql_for_model(model, style, connection):
         sql_files.append(os.path.join(app_dir, "%s.sql" % opts.model_name))
     for sql_file in sql_files:
         if os.path.exists(sql_file):
-            with codecs.open(sql_file, 'U', encoding=settings.FILE_CHARSET) as fp:
+            with codecs.open(sql_file, 'r' if six.PY3 else 'U', encoding=settings.FILE_CHARSET) as fp:
                 # Some backends can't execute more than one SQL statement at a time,
                 # so split into separate statements.
                 output.extend(_split_statements(fp.read()))