GPG homedir path length limit

[John Lane]

Just experimenting in a sandbox homedir, I noticed that the homedir path
needs to be below a certain size.

    $ pwd


/home/user/aaaaa/bbbbbbbb/cccccccc/dddd/eee/fffffffffff/ggggggggggggggggggggggg

    $ mkdir -m 700 alice.gpg

    $ gpg --homedir alice.gpg --gen-key

    gpg: can't connect to the agent: IPC connect call failed

    $ gpg-agent --homedir alice.gpg --daemon

    gpg-agent[3857]: socket name
'/home/user/aaaaa/bbbbbbbb/cccccccc/dddd/eee/fffffffffff/ggggggggggggggggggggggg/alice.gpg/S.gpg-agent.extra'
is too long


Changing to a shorter path works fine.