Remove duplicate code

src/Mod/AddonManager/addonmanager_workers.py

@@ -304,11 +304,9 @@ class FillMacroListWorker(QtCore.QThread):
         self.info_label_signal.emit("Downloading list of macros from the FreeCAD wiki...")
         self.progressbar_show.emit(True)
         u = utils.urlopen("https://www.freecadweb.org/wiki/Macros_recipes")
-        if u is None:
+        if not u:
             FreeCAD.Console.PrintWarning(translate('AddonsInstaller', 'Appears to be an issue connecting to the Wiki, therefore cannot retrieve Wiki macro list at this time')+"\n")
             return
-        if not u:
-           return
         p = u.read()
         u.close()
         if sys.version_info.major >= 3 and isinstance(p, bytes):