Did WMCmd.vbs change recently to require correct input file extens

I have been using WMCmd.vbs to convert audio and video files as follows:

CScript.exe WMCmd.vbs -input inFN -output outFN

However, I noticed that it started failing on files of some input formats if
the extension of the input file does not match to the type. For instance, it
so happens that files that I need to convert all come with extension "tmp".
Before, it would properly convert all such files regardless of the format of
that file. Now, at least for two two input formats -- MPEG and 3GP -- if I do
not change the extension of the input to "mpg" or "3gp", respectively, then
conversion fails with the "codec not found" error message. If I rename the
same input file and change its extesnion to "3gp", conversion works fine. E.g.

CScript.exe WMCmd.vbs -input input3GP.3gp -output output.wmv

works,while

CScript.exe WMCmd.vbs -input input3GP.tmp -output output.wmv

does not.

Is this a recent change? In any case, is there an option that would allow me
to convert correctly without worrying abut file extensions?

Thanks!