Arguably we don't need this feature any more.  The only reasonable way to implement it would be to slurp the entire contents of the file into a string and then exec that.  The caller might as well do this.  Alternatively one could use execfile() (which takes a filename instead of a stream).  The only advantage of using exec(<stream>) might be that it would deal with encoding declarations transparantly; but we should probably have a way to handle those somewhere in the library anyway, as it's also necessary for other tools (e.g. modulefinder.py, pyclbr.py and linecache.py).  Alternatively I'm not so sure that we will need to support encoding declarations forever -- I'm hoping that at some point UTF-8 and BOM+UTF-16 will take over the world.