I'm experiencing the same issue with gnupg-agent 2.1.7-2 from unstable. The cause is that "gpg-agent --daemon" now returns "2" instead of "0" if the daemon is already running, which is not accepted as a valid return by older versions of keychain.
This seems to issue #30 in keychain's github [1]. While the title suggests that it's specific to OSX, it sounds like exactly the same problem. The issue was fixed with the commit bf30f9188 [2]. Cheers, Boris [1] https://github.com/funtoo/keychain/issues/30 [2] https://github.com/funtoo/keychain/commit/bf30f9188aa07782cd738da2e5e3
