confusing error message in os.rename (bug?)

[Wolfram Ladurner <wl@...>]

$ touch testfile
$ lua -e 'assert( os.rename( "testfile", "/does/not/exist" ) )'
lua: <command line>:1: testfile: No such file or directory
stack traceback:
        [C]: in function `assert'
        <command line>:1: in main chunk
        [C]: ?

The error message looks like the testfile does not exist, while it is 
the new name that is causing the error.

--
Wolfram Ladurner