Refuse a held-back membership's old wrapper in the tool runner, pinning mesh-sdk's review-round-1 codec

The old grants part wrote its wrapper for a held-back membership too; the new part leaves such a key alone, and taking
it would serve what the hold kept back with the stream's copy ignored. The integration test now proves that copy is
served instead. Review round 1 of issue 774's fix.

node-tools/internal/bus/bus.go

@@ -470,8 +470,9 @@ func (c *Conn) followGrants(module string) {
 			return // a membership withdrawn is the stream's, or the module's unassignment's, to say
 		}
 		// Read through mesh-sdk's one codec of this state, the grants part's writer's (issue 774): it takes the bare
-		// membership and the wrapper the part wrote before, and refuses a value naming no node or module, which then
-		// leaves the assignments stream's copy in force instead of an empty membership.
+		// membership and a wrapper the part wrote before of one published or unchanged, and refuses a held-back one's
+		// wrapper or a value naming no node or module, which then leaves the assignments stream's copy in force instead.
+		// A refused value arriving after a good one keeps the last good membership: nothing here clears it.
 		var m Membership
 		body, err := membership.BareGrantsMembership(e.Value())
 		if err == nil {

node-tools/internal/bus/state_watch_test.go

@@ -125,7 +125,13 @@ func TestAMembershipTheGrantsPartWroteWrappedIsServed(t *testing.T) {
 	mesh.Bucket(t, "gitea_repos")
 	gitea := mt.MembershipOf("gitea", "anchor", false, nil)
 	gitea.State = []bus.StateIssued{{Name: "repos", Bucket: "gitea_repos", Writes: true}}
-	mesh.IssueInGrantsWrapped(t, gitea)
+	mesh.IssueInGrantsWrapped(t, gitea, "published")
+	// The old wrapper of a membership the part held back carries its unpublished composition: refused, so the
+	// assignments stream's copy is served, never what the hold kept back.
+	pages := mt.MembershipOf("pages", "anchor", false, nil)
+	mesh.Issue(t, pages)
+	heldBack := mt.MembershipOf("pages", "anchor", true, nil)
+	mesh.IssueInGrantsWrapped(t, heldBack, "not published, a shadow difference: publishing would lose the last holder of x")
 	conn, err := bus.Connect(bus.Credential{URL: mt.URL(t), Module: "node-tools", Node: "anchor"})
 	if err != nil {
 		t.Fatal(err)
@@ -148,6 +154,16 @@ func TestAMembershipTheGrantsPartWroteWrappedIsServed(t *testing.T) {
 	if e, err := conn.StateGet("gitea", "repos", "novox.hq"); err != nil || e == nil || string(e.Value) != `{"v":1}` {
 		t.Errorf("the state reads back %+v, %v", e, err)
 	}
+	conn.Follow("pages")
+	mt.Until(t, func() error {
+		if m := conn.Membership("pages"); m == nil || len(m.Serves) == 0 {
+			return fmt.Errorf("pages' membership is %+v, want the assignments stream's", m)
+		}
+		return nil
+	})
+	if got, want := fmt.Sprint(conn.ServedOn("pages", "pages_list")), "[{mesh.mod.pages.tool.pages_list.anchor }]"; got != want {
+		t.Errorf("a held-back membership's wrapper is served: pages_list on %s, want the stream's %s", got, want)
+	}
 }
 
 // owedWatcher is the gitea module's view of the checker's owed: the bucket, and a runtime connection