Fixed #18091 -- Non-ASCII templates break `django-admin.py startproject --template=TEMPLATE`.

Thanks to Claude Huchet and Tomáš Ehrlich for the patch.

django/core/management/templates.py

@@ -8,6 +8,8 @@ import shutil
 import stat
 import sys
 import tempfile
+import codecs
+
 try:
     from urllib.request import urlretrieve
 except ImportError:     # Python 2
@@ -154,12 +156,12 @@ class TemplateCommand(BaseCommand):
 
                 # Only render the Python files, as we don't want to
                 # accidentally render Django templates files
-                with open(old_path, 'r') as template_file:
+                with codecs.open(old_path, 'r', 'utf-8') as template_file:
                     content = template_file.read()
                 if filename.endswith(extensions) or filename in extra_files:
                     template = Template(content)
                     content = template.render(context)
-                with open(new_path, 'w') as new_file:
+                with codecs.open(new_path, 'w', 'utf-8') as new_file:
                     new_file.write(content)
 
                 if self.verbosity >= 2:

tests/regressiontests/admin_scripts/custom_templates/project_template/ticket-18091-non-ascii-template.txt

@@ -0,0 +1,2 @@
+Some non-ASCII text for testing ticket #18091:
+üäö €

tests/regressiontests/admin_scripts/tests.py

@@ -1573,3 +1573,16 @@ class StartProject(LiveServerTestCase, AdminScriptTestCase):
         self.assertOutput(err, "Destination directory '%s' does not exist, please create it first." % testproject_dir)
         self.assertFalse(os.path.exists(testproject_dir))
 
+
+    def test_custom_project_template_with_non_ascii_templates(self):
+        "Ticket 18091: Make sure the startproject management command is able to render templates with non-ASCII content"
+        template_path = os.path.join(test_dir, 'admin_scripts', 'custom_templates', 'project_template')
+        args = ['startproject', '--template', template_path, '--extension=txt', 'customtestproject']
+        testproject_dir = os.path.join(test_dir, 'customtestproject')
+
+        out, err = self.run_django_admin(args)
+        self.addCleanup(shutil.rmtree, testproject_dir)
+        self.assertNoOutput(err)
+        self.assertTrue(os.path.isdir(testproject_dir))
+        self.assertEqual(open(os.path.join(testproject_dir, 'ticket-18091-non-ascii-template.txt')).read(),
+                         'Some non-ASCII text for testing ticket #18091:\n\xc3\xbc\xc3\xa4\xc3\xb6 \xe2\x82\xac\n')