Steps to reproduce:
Get a blah.ufraw file created with a pre-lensfun enabled version of UFRaw, i. g. 0.15. This will have no <lensfun></lensfun> tag whatsoever.
Run an UFRaw version with lensfun enabled (0.19.2-2) using: ufraw-batch --conf=blah.ufraw *.nef.
Result: Lensfun corrections will be used. This can cause trouble since depending on the crop size black borders will be visible.
Conclusion: Recent versions of UFRaw (containing Lensfun) should treat configuration files from legacy versions of UFRaw as if the user explicitly decided to deactivate Lensfun.
I've played with UFRaw a bit more and whatever I try, I seem not to be able to reproduce the issue above. If the
section is missing from the .ufraw recipe, it doesn't matter what value the
entry in .ufrawrc has. No Lensfun correction, neither with ufraw, nor with ufraw-batch. Sorry for the confusion, I really can't say what happened.
I close this bug report since the OP cannot reproduce the problem.
Regards,
Niels Kristian