Assertion failed Error when trying to run DNG->GPR with CR2 converted to DNG

Hey, 

Is it possible to convert DNG made from CR2 to GPR?
When trying to run the command, I got this error:
```
Assertion failed: (src_exif->fSoftware.Length() < sizeof(dst_exif->software_version)), function convert_dng_exif_to_dng_exif_info, file gpr.cpp, line 446.
[1]    63753 abort      build/source/app/gpr_tools/gpr_tools -i ./60d_orig.DNG -o converted.GPR
```