TO SQUASH: Address review comments.

oauth2client/_helpers.py

@@ -184,6 +184,35 @@ def string_to_scopes(scopes):
         return scopes
 
 
+def update_query_params(uri, params):
+    """Updates a URI with new query parameters.
+
+    If a given key from ``params`` is repeated in the ``uri``, then
+    the new value from ``params`` will be added to that list. If the
+    key occurs zero or once in the ``uri``, the value from ``params``
+    will be used as the only value.
+
+    Args:
+        uri: string, A valid URI, with potential existing query parameters.
+        params: dict, A dictionary of query parameters.
+
+    Returns:
+        The same URI but with the new query parameters added.
+    """
+    parts = urllib.parse.urlparse(uri)
+    query_params = urllib.parse.parse_qs(parts.query)
+    for key, value in six.iteritems(params):
+        curr_vals = query_params.setdefault(key, [])
+        if len(curr_vals) > 1:
+            curr_vals.append(value)
+        else:
+            curr_vals[::] = [value]
+
+    new_query = urllib.parse.urlencode(query_params, doseq=True)
+    new_parts = parts._replace(query=new_query)
+    return urllib.parse.urlunparse(new_parts)
+
+
 def _add_query_parameter(url, name, value):
     """Adds a query parameter to a url.
 
@@ -199,7 +228,8 @@ def _add_query_parameter(url, name, value):
     """
     if value is None:
         return url
-    return update_query_params(url, {name: value})
+    else:
+        return update_query_params(url, {name: value})
 
 
 def validate_file(filename):
@@ -297,35 +327,6 @@ def _urlsafe_b64decode(b64string):
     return base64.urlsafe_b64decode(padded)
 
 
-def update_query_params(uri, params):
-    """Updates a URI with new query parameters.
-
-    If a given key from ``params`` is repeated in the ``uri``, then
-    the new value from ``params`` will be added to that list. If the
-    key occurs zero or once in the ``uri``, the value from ``params``
-    will be used as the only value.
-
-    Args:
-        uri: string, A valid URI, with potential existing query parameters.
-        params: dict, A dictionary of query parameters.
-
-    Returns:
-        The same URI but with the new query parameters added.
-    """
-    parts = urllib.parse.urlparse(uri)
-    query_params = urllib.parse.parse_qs(parts.query)
-    for key, value in six.iteritems(params):
-        curr_vals = query_params.setdefault(key, [])
-        if len(curr_vals) > 1:
-            curr_vals.append(value)
-        else:
-            curr_vals[::] = [value]
-
-    new_query = urllib.parse.urlencode(query_params, doseq=True)
-    new_parts = parts._replace(query=new_query)
-    return urllib.parse.urlunparse(new_parts)
-
-
 def parse_unique_urlencoded(content):
     """Parses unique key-value parameters from urlencoded content.