debdiff task extra_argument --diffstat being ignored: missing diffstat package

Problem: creating a work request with extra_args and using --diffstat: the output does not contain the --diffstat.

The reason is that the environment might not have the package diffstat, debdiff is ignoring it.

After looking at debdiff, we should also make sure that wdiff is installed (for --wdiff-source-control valid flag).

I see that debdiff also checks if interdiff binary is available from patchutils package is available, but not sure for which flag.