I was hit by this, and created https://github.com/ueno/ruby-gpgme/pull/166. Won't have much time on this topic however.
- Bug#1024651: ruby-gpgme: FTBFS against libgpgme-dev >= ... Andreas Metzler
- Bug#1024651: ruby-gpgme: FTBFS against libgpgme-dev &... Mathieu Parent