Merge branch 'jk/ssh-signing-fix'

Reject OpenSSH 8.7 whose "ssh-keygen -Y find-principals" is
unusable from running the ssh signature tests.

* jk/ssh-signing-fix:
  t/lib-gpg: avoid broken versions of ssh-keygen

t/lib-gpg.sh

@@ -104,6 +104,12 @@ test_lazy_prereq GPGSSH '
 	test $? != 127 || exit 1
 	echo $ssh_version | grep -q "find-principals:missing signature file"
 	test $? = 0 || exit 1;
+
+	# some broken versions of ssh-keygen segfault on find-principals;
+	# avoid testing with them.
+	ssh-keygen -Y find-principals -f /dev/null -s /dev/null
+	test $? = 139 && exit 1
+
 	mkdir -p "${GNUPGHOME}" &&
 	chmod 0700 "${GNUPGHOME}" &&
 	(setfacl -k "${GNUPGHOME}" 2>/dev/null || true) &&