Change logging statements to not use the "%" operator.

third_party/WebKit/Tools/Scripts/webkitpy/common/net/rietveld.py

Index: third_party/WebKit/Tools/Scripts/webkitpy/common/net/rietveld.py
diff --git a/third_party/WebKit/Tools/Scripts/webkitpy/common/net/rietveld.py b/third_party/WebKit/Tools/Scripts/webkitpy/common/net/rietveld.py
index 9d276cc98237bfa746e0f423ca0bc006a851abf7..8780b920c6f2d2de56bb2dc77e9c954d3cd25d3c 100644
--- a/third_party/WebKit/Tools/Scripts/webkitpy/common/net/rietveld.py
+++ b/third_party/WebKit/Tools/Scripts/webkitpy/common/net/rietveld.py
@@ -65,12 +65,12 @@ def _get_json(url, web):
     try:
         contents = web.get_binary(url)
     except urllib2.URLError:
-        _log.error('Request failed to URL: %s' % url)
+        _log.error('Request failed to URL: %s', url)
         raise
     try:
         return json.loads(contents)
     except ValueError:
-        _log.error('Invalid JSON: %s' % contents)
+        _log.error('Invalid JSON: %s', contents)
         raise