Loading old project files leads to wrongly calibrated images

When loading project files from version 0.8 the image is not undistorted correctly:

Apparently there were variables k4, k5, and k6` which were not present in more recent version, and got re-added with the extended model. Hence, the parameters occur in the pet-file and are read and stored correctly in the UI, but are used for undistortion when not needed.

pet-file:

...
 <INTRINSIC_PARAMETERS 
    TY="-0.000557" 
    K5="0" <--- should this be set loaded?
    QUAD_ASPECT_RATIO="0" 
    FIX_CENTER="0" 
    R4="0.049984" 
    R2="-0.138423" 
    ENABLED="1" 
    TANG_DIST="1" 
    K6="0"  <--- should this be set loaded?
    R6="-0.037627" 
    CY="1199.99" 
    TX="-0.001076" 
    K4="2" <--- should this be set loaded?
    FX="2611.68" 
    FY="2607.88" 
    CX="2058.2"
  />
...

To reproduce: sime/export/Samstag/4k/*.pet