Check content type by completely match instead of partial match

Currently, 'get_content_type' method in neutron/wsgi.py checks
specified format by 'in' statement.
Thus, string(e.g. 'application/j') that is partial matched to
'application/json' is returned.

However, we cannot find valid serializer from the format,
and request fails with unexpected error.

Change-Id: I75aac0308d0fd0321973c4bda3bc07ca0224e1c1
Closes-Bug: #1612485

neutron/tests/unit/api/v2/test_resource.py

@@ -43,6 +43,12 @@ class RequestTestCase(base.BaseTestCase):
         result = request.get_content_type()
         self.assertEqual("application/json", result)
 
+    def test_content_type_with_partial_matched_string(self):
+        request = wsgi.Request.blank('/tests/123')
+        request.headers["Content-Type"] = "application/j"
+        result = request.best_match_content_type()
+        self.assertEqual("application/json", result)
+
     def test_content_type_from_accept(self):
         content_type = 'application/json'
         request = wsgi.Request.blank('/tests/123')

neutron/wsgi.py

@@ -252,7 +252,7 @@ class Request(wsgi.Request):
         return bm or 'application/json'
 
     def get_content_type(self):
-        allowed_types = ("application/json")
+        allowed_types = ("application/json",)
         if "Content-Type" not in self.headers:
             LOG.debug("Missing Content-Type")
             return None