Gen from scancode JSON does not work

[pombredanne]

Reported privately:

I'm getting an error 'CRITICAL: The essential field 'about_file_path' is not found.' Not sure what I'm missing or the necessary workflow steps.
Currently I have the output files from scancode-toolkit.
Previously we went from scancode to aboutcode.
This is with aboutcode-toolkit-3.3.2 and scancode-toolkit-2.9.2
Scanned to json-pp and trying to generate about files
/opt/scancode/scancode-toolkit-2.9.2/scancode -l -p -c --json-pp ~/src/scancode.json ~/src/codebase/
./about gen ~/src/scancode.json ~/src/about

[chinyeungli]

#364 is fixed and the about_file_path is no longer needed for the input.