Trac #15811: Random doctest failure in maxima_abstract.py

This is yet again due to terminal echo showing up in unexpected places.

URL: http://trac.sagemath.org/15811
Reported by: vbraun
Ticket author(s): Volker Braun
Reviewer(s): Jean-Pierre Flori

src/sage/interfaces/maxima.py

@@ -756,7 +756,8 @@ def _eval_line(self, line, allow_use_file=False,
         line_echo = self._expect.readline()
         if not wait_for_prompt:
             return
-        assert line_echo.strip() == line.strip(), 'mismatch:\n' + line_echo + line
+        # line_echo sometimes has randomly inserted terminal echo in front #15811
+        assert line_echo.strip().endswith(line.strip()), 'mismatch:\n' + line_echo + line
 
         self._expect_expr(self._display_prompt)
         out = self._before()        # input echo + output prompt + output