Skip empty arch when searching other strings of same model

review397006

trytond/ir/ui/view.py

@@ -140,7 +140,10 @@ class View(ModelSQL, ModelView):
                     ('module', '=', view.module),
                     ])
                 for view2 in self.browse(view_ids):
-                    tree2 = etree.fromstring(view2.arch)
+                    xml2 = view2.arch.strip()
+                    if not xml2:
+                        continue
+                    tree2 = etree.fromstring(xml2)
                     root2_element = tree2.getroottree().getroot()
                     strings += self._translate_view(root2_element)
             if not strings: