access/sftp doesn't build with libssh2-1.8.1
The change in commit afee1e72a8e08866bbe35d1a57e859cac81052b4, which added some new ECDSA key types conditional on libssh2 being version 1.8.1 or later, seems to be a bit premature. libssh2 1.8.1 has been released and it doesn't include the new key types (although the master version of libssh2 does), so building sftp.c fails:
access/sftp.c:311:42: error: 'LIBSSH2_KNOWNHOST_KEY_ECDSA_256' undeclared
Maybe revert this commit until there's a libssh2 release that does include the new constants?