don’t look for plux library if already on sys.path

src/bitalino/__init__.py

@@ -26,10 +26,12 @@ if platform.mac_ver()[0] != "":
             )
             sys.exit(1)
 
-base_path = importlib.util.find_spec("plux").submodule_search_locations
-if base_path is not None and len(base_path) == 1:
-    plux_path = f"{base_path[0]}/PLUX-API-Python3/{osDic[platform.system()]}"
-    print(f"Found plux lib: {plux_path}")
-    sys.path.append(plux_path)
-else:
-    print("Could not find plux lib, should be in bitalino/src/plux/.")
+spec = importlib.util.find_spec("plux")
+if spec.loader is None:
+    base_path = spec.submodule_search_locations
+    if base_path is not None and len(base_path) == 1:
+        plux_path = f"{base_path[0]}/PLUX-API-Python3/{osDic[platform.system()]}"
+        print(f"Found plux lib: {plux_path}")
+        sys.path.append(plux_path)
+    else:
+        print("Could not find plux lib, should be in bitalino/src/plux/.")