Python 3: decode bytes before feeding them to jsonutils.loads()

urlopen(...).read() returns bytes in Python 3, so we cannot call
jsonutils.loads() on the output: we first have to decode() it.

Change-Id: I39504059a8c82347476dd88dfcbd060d58df13d0

heatclient/v1/shell.py

@@ -14,6 +14,7 @@
 #    under the License.
 
 import logging
+import six
 from six.moves.urllib import request
 import yaml
 
@@ -647,6 +648,8 @@ def do_resource_signal(hc, args):
         data_url = template_utils.normalise_file_path_to_url(data_file)
         data = request.urlopen(data_url).read()
     if data:
+        if isinstance(data, six.binary_type):
+            data = data.decode('utf-8')
         try:
             data = jsonutils.loads(data)
         except ValueError as ex: