`--pinentry-mode error` cannot be used with gpg-agent "extra" socket

Over on HBASE-27312, we found an issue in our release automation, which relies on using this plugin and a GnuPG agent for performing builds inside of an isolated environment. With GPG version >= 2.1, the plugin will make use of --pinentry-mode error. This feature appears to not be available using the "extra" gpg-agent socket. We had to "upgrade" to using the "standard" socket, which probably exposes more gpg features to the isolated environment than we would like.