* 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

When merging a signed tag fmt-merge-msg was unable to verify its
validity missing the necessary ssh allowedSignersFile config.

Adds gpg config parsing to fmt-merge-msg.
Adds tests for ssh signed tags to fmt-merge-msg tests.

Signed-off-by: Fabian Stelzer <fs@gigacodes.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

facca53 added verification for ssh signatures but incorrectly
described the usage of gpg.minTrustLevel. While the verifications
trustlevel is stil set to fully or undefined depending on if the key is
known or not it has no effect on the verification result. Unknown keys
will always fail verification. This commit updates the docs to match
this behaviour.

Signed-off-by: Fabian Stelzer <fs@gigacodes.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

We xmemdupz() this buffer, but never free it. Let's do so. We'll use a
cleanup label, since there are multiple exits from the function.

Note that it was also declared a "const char *". We could switch that to
"char *" to indicate that it's allocated, but that make it awkward to
use with skip_prefix(). So instead, we'll introduce an extra non-const
pointer.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

We read stdout from gpg into a strbuf, then split it into a list of
strbufs, pull out one element, and return it. But we don't free either
the original stdout buffer, nor the list returned from strbuf_split().

This patch fixes both. Note that we have to detach the returned string
from its strbuf before calling strbuf_list_free(), as that would
otherwise throw it away.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>