i3, screen-lock: the session's output to the journal, and the colour locker removed before i3lock is checked

lemurs leaves the session a stdout nobody reads, so a program writing to it dies of EPIPE.
i3lock-color provides i3lock, so with it still installed the host saw i3lock as present,
skipped the install and then removed the only locker; removing it first lets the same
apply install i3lock.

modules/i3/cmd/i3-tools/manifest_test.go

@@ -151,7 +151,7 @@ func TestTheLoginManagersEntryRunsTheSessionsStart(t *testing.T) {
 	if r["path"] != "/etc/lemurs/wms/i3" || r["mode"] != "0755" {
 		t.Fatalf("%v", r)
 	}
-	if !strings.Contains(r["content"].(string), `exec /bin/sh "$HOME/.xinitrc"`) {
+	if !strings.Contains(r["content"].(string), `exec systemd-cat -t x-session /bin/sh "$HOME/.xinitrc"`) {
 		t.Fatal("the entry runs the session's start, never i3 bare")
 	}
 	pkgs := map[string]bool{}