shell-completion: fix completion of `systemctl --user unset-environment` (#37409)

Co-authored-by: Eisuke Kawashima <e-kwsm@users.noreply.github.com>

diff --git a/shell-completion/zsh/_systemctl.in b/shell-completion/zsh/_systemctl.in
index 0000147fe42f24c9f6f6d235266b3fb141ccbeb9..16e43d0f12e4ecea73b7b10242e8e5c8f3fa3680 100644 (file)
--- a/shell-completion/zsh/_systemctl.in
+++ b/shell-completion/zsh/_systemctl.in
@@ -413,7 +413,7 @@ for fun in set-environment unset-environment ; do
             suf='-S='
         fi
         _wanted systemd-environment expl 'environment variable' \
-                compadd "$@" ${suf} - ${${(f)"$(systemctl show-environment)"}%%=*}
+                compadd "$@" ${suf} - ${${(f)"$(systemctl "$_sys_service_mgr" show-environment)"}%%=*}
     }
 done