When devtool updated llvm in:
   llvm: upgrade 19.1.7 -> 20.1.0
the explicit PV variable was retained.

Whoever takes this bug should:
 - revert the upgrade locally and 
 - try the devtool upgrade again
to see if PV is essential to the recipe 
or 

if devtool can drop the explicit PV  (which is normally derived from the 
recipe filename_version convention) 

or 

issue a warning that the devtool user should review and resolve manually.

If this is beyond devtool's abilities, perhaps the limitation should be documented.