Merge branch 'hi/gpg-optional-pkfp-fix'

The code to parse GPG output used to assume incorrectly that the
finterprint for the primary key would always be present for a valid
signature, which has been corrected.

* hi/gpg-optional-pkfp-fix:
  gpg-interface: limit search for primary key fingerprint
  gpg-interface: refactor the free-and-xmemdupz pattern

diff --cc t/t4202-log.sh
Simple merge