Comment 6 for bug 691836

From my point of view the proposed fix only makes the bug less likely to occur, but does not fix it.

The likelihood of occurrence of '%mys' in a sequence of characters is very difficult to predict when you are storing blob/text. The proposed fix for example would fail if I were to store the python source or this bug description as text as '%mys' occurs in it. When you are storing data from the web, you want something that always works.

Also, while I did not do any performance tests, using replace without start index hint, cause the string to be rescanned from the start which can be slow when you are manipulating large text/blob.

That being said there may be a simpler fix than the one I did (though it also check if all args where used in addition to fixing the bug).