feature: Implement both cases where an optional dependency becomes explicit.

armarx_setup/core/module_graph.py

@@ -51,10 +51,15 @@ class ModuleGraph(nx.DiGraph):
             self.add_module(required_module, ws=module.ws)
 
         # Add optional dependencies.
+        for _, module_in_graph in self.nodes(data="module"):
+            # If this module is an optional dependency of any module in the graph,
+            # make it required now to retain correct order.
+            if module.name in module_in_graph.optional_modules:
+                self.add_edge(module_in_graph.name, module.name)
         for optional_name in module.optional_modules:
-            # If the dependency is already in the graph, it is a manually set
-            # dependency through the workspace or via a required_module earlier,
-            # and thus not optional.
+            # If an optional dependency of this module is already in the graph, it
+            # was either manually set in the workspace or via a required_module earlier.
+            # Make it an explicit dependency in the graph in this case.
             if optional_name in self:
                 self.add_edge(module.name, optional_name)