* fs/ssh-signing:
ssh signing: test that gpg fails for unknown keys
ssh signing: tests for logs, tags & push certs
ssh signing: duplicate t7510 tests for commits
ssh signing: verify signatures using ssh-keygen
ssh signing: provide a textual signing_key_id
ssh signing: retrieve a default key from ssh-agent
ssh signing: add ssh key format and signing code
ssh signing: add test prereqs
ssh signing: preliminary refactoring and clean-up