Re-scrub derivations returned by override and overrideAttrs so package modules cannot restore real dependency graphs during test evaluation. Adapt affected tests with explicit runtime dependencies, executable mocks, and absence assertions.
PR #9420 added set-SSH_AUTH_SOCK.service and ordered it before sshAuthSock.systemd.socketProviderUnit. When that provider is a socket unit, systemd default dependencies already order the socket before sockets.target while service defaults place set-SSH_AUTH_SOCK.service after basic.target. That creates a sockets.target -> basic.target -> set-SSH_AUTH_SOCK.service -> provider.socket -> sockets.target cycle.
For gpg-agent this makes systemd drop gpg-agent-ssh.socket, leaving SSH_AUTH_SOCK pointing at the expected S.gpg-agent.ssh path but with no socket listening there.
Only order and install the environment service against non-socket providers. Socket providers still get SSH_AUTH_SOCK imported through default.target.
Fixes#9432.
`SSH_AUTH_SOCK` is exported in shells only, which systemd does not
inherit from. With this commit, it is also set in systemd such that
systemd-managed applications can access the SSH agent by declaring
dependencies onto 'sshAuthSock.systemd.socketProviderUnit'.
Closes#7971.
This reverts commit 9dc93220c1.
On one hand, conflicting definitions for `sshAuthSock.initialization.*`
were triggering before the assertion triggered, hereby making the
assertion redundant. On the other hand, the assertion prevents users
from running multiple agents side-by-side even after resolving the
definition conflict.
See https://github.com/nix-community/home-manager/pull/8533#issuecomment-4224165151.
