#21 keep backup of question source files

[Anonymous]

It has been reported by users that while editing the quiz
souce file that the source is overwritten by an empty
file when the user clicks on "Save and Recompile". This
occurs when the server is busy. I am not quite sure
what exactly the users did (like resubmit the request).
But it would seem a good idea if the system could keep
an automatic backup of the source.