Fix error: variable 'kw' referenced before assignment

Change-Id: Ife95d74bf645687dc4595b16434c88ee874c2f95
Closes-bug: #1311742

tests/rest/test_args.py

@@ -0,0 +1,20 @@
+import mock
+import unittest
+
+from wsme import exc
+from wsme.rest import args
+from wsme.rest import json
+
+
+class TestArgs(unittest.TestCase):
+
+    def test_args_from_body(self):
+
+        funcdef = mock.MagicMock()
+        body = mock.MagicMock()
+        mimetype = "application/json"
+        funcdef.ignore_extra_args = True
+        json.parse = mock.MagicMock()
+        json.parse.side_effect = (exc.UnknownArgument(""))
+        resp = args.args_from_body(funcdef, body, mimetype)
+        self.assertEqual(resp, ((), {}))

wsme/rest/args.py

@@ -232,6 +232,7 @@ def args_from_body(funcdef, body, mimetype):
     except UnknownArgument:
         if not funcdef.ignore_extra_args:
             raise
+        kw = {}
 
     return (), kw