Function log_sig_data 

pub(crate) fn log_sig_data(signature: &OpenpgpSignature) -> String

Creates a representative string for logging from an OpenpgpSignature.

The returned string is of the form “fingerprint (file)” where “fingerprint” is the list of issuer fingerprints of the signature and “file” is the optional path of a file from which the OpenPGP signature has been read.