Exported workflow (.nwf) file will not import; claims it is a (.uda). Saddness.

I have a workflow that was written as a site workflow, then moved into a 'site' user-defined function.   Realizing this was wrong, we properly converted it to a .uda and imported it with CentralAdmin.  All is well, the udf works properly.

When we did these steps, we exported the workflow as an .nwf, then converted it to a .uda.  I have both files, the .nwf and .uda files.  The files are clearly different.  The .nwf is a blob of clear-text ASCII, the .uda is an .xml file.   

Trying to import the .nfw back into a new workflow in order to review the code, we get an error along the lines : "I can't do that dave.  This is a .uda."

Is there a way to (de-compile) the code and return it to an editable file? 
It appears we should have saved the .nwf file earlier in the process.