convert: Non-conforming drawing primitive definition `image'

Hello all,

A small bug with convert:

   convert some_image.png -draw "image src-over 0,0 0,0 1.png" out.png

Yields this error:

  convert: Non-conforming drawing primitive definition `image'.

The problem being that it cannot handle image names that start with
numbers.  (Chaning 1.png to a1.png prevents the error.)

I'm on Ubuntu Linux with ImageMagick 6.3.7.

Thanks for all the hard work!
- Adam