Remove translation marker.

I don't think this needs translation. It is a key: value display
with no written language.

Author: rouilj

roundup/cgi/templating.py

@@ -1183,7 +1183,7 @@ def history(self, direction='descending', dre=re.compile(r'^\d+$'),
                         # property no longer exists
                         comments['no_exist'] = self._(
                             "<em>The indicated property no longer exists</em>")
-                        cell.append(self._('<em>%s: %s</em>\n')
+                        cell.append('<em>%s: %s</em>\n'
                                     % (self._(k), str(args[k])))
                         continue