Avoid None parsing member data

Change-Id: I508353990f67fce641f409c204e6d1c5dea3b5da

stackalytics/processor/mps.py

@@ -38,11 +38,12 @@ def strip_garbage(s):
 
 def _retrieve_member(uri, member_id, html_parser):
 
-    content = six.text_type(utils.read_uri(uri), 'utf8')
+    content = utils.read_uri(uri)
 
     if not content:
         return {}
 
+    content = six.text_type(content, 'utf8')
     member = {}
 
     for rec in re.finditer(NAME_AND_DATE_PATTERN, content):