issue2551069 - when unsupported type is found report type

When reporting an unsupported response type, error 406, report what
type is seen by the code. Allows the user to better debug the
query. E.G. look at the url and see if they mistyped it (e.g. by
leaving a ? out of the url), or a mispelled accept header value or
....

Author: rouilj

roundup/rest.py

@@ -1985,8 +1985,8 @@ def dispatch(self, method, uri, input):
             # error out before doing any work if we can't
             # display acceptable output.
             self.client.response_code = 406
-            output = ( "Requested content type is not available.\n"
-                       "Acceptable types: %s"%(
+            output = ( "Requested content type '%s' is not available.\n"
+                       "Acceptable types: %s"%(data_type,
                            ", ".join(self.__accepted_content_type.keys())))
 
         # Make output json end in a newline to

test/rest_common.py

@@ -1544,7 +1544,8 @@ def testDispatch(self):
 
 
         # TEST #8
-        # DELETE: delete issue 1
+        # DELETE: delete issue 1 also test return type by extension
+        #         test bogus extension as well.
         etag = calculate_etag(self.db.issue.getnode("1"),
                               self.db.config['WEB_SECRET_KEY'])
         etagb = etag.strip ('"')
@@ -1569,11 +1570,20 @@ def testDispatch(self):
                             "/rest/data/issue/1.json",
                             form)
         self.assertEqual(self.server.client.response_code, 200)
-        json_dict = json.loads(b2s(results))
         print(results)
+        json_dict = json.loads(b2s(results))
         status=json_dict['data']['status']
         self.assertEqual(status, 'ok')
 
+        results = self.server.dispatch('DELETE',
+                            "/rest/data/issue/1issue:=asdf.jon",
+                            form)
+        self.assertEqual(self.server.client.response_code, 406)
+        print(results)
+        response="Requested content type 'jon' is not available.\n" \
+                 "Acceptable types: */*, application/json, application/xml\n"
+        self.assertEqual(results, response)
+
         # TEST #9
         # GET: test that version can be set with accept:
         #    ... ; version=z