Test fail when default socket name <build folder>/test/openpgp/S.gpg-agent is
longer than 108 character.
Solution would be using socket redirect directive in S.gpg-agent:
%Assuan%
socket=/tmp/gpg-<temp>/S.gpg-agent

gpg-agent does not support socket redirect.
Suggested solutions:
a) Implement redirect feature in gpg-agent code.
b) Use assuan_sock_connect.