Let a provider serve its consumers its own composed names (hq ADR 0346, issue 624)

The forge writes every package tarball at its public name, and its
consumers had no source for that name but a second copy kept by hand,
though the mesh composes it for the forge's route. A served value may now
name the provider's own names; a name its machine does not compose leaves
the key out, and the plan says so.

internal/catalogue/bound.go

@@ -127,6 +127,7 @@ func boundNeed(n Needed, bound Chosen, catalogue map[string]Manifest, node Node,
 		identity = pm.IdentityBoundOf(n.Name)
 	}
 	held.From, held.At, held.Module, held.Serves, held.Identity = p.Node, p.At, p.Module, p.Serves, identity
+	held.LeftOut = p.LeftOut
 	return held, true, ""
 }