Fix test on older Python versions

Author: brownbaerchen

pySDC/tests/test_controllers/test_controller_ParaDiag_nonMPI.py

@@ -250,7 +250,8 @@ def test_ParaDiag_convergence_rate(L, M, N, alpha):
     uend, stats = controller.run(u0=u0, t0=0, Tend=L * dt)
 
     # test that the convergence rate in the first iteration is sufficiently small.
-    errors = get_sorted(stats, type='e_global_post_iteration', sortby='iter', time=(L - 1) * dt)
+    t_last = max([me[0] for me in get_sorted(stats, type='e_global_post_iteration')])
+    errors = get_sorted(stats, type='e_global_post_iteration', sortby='iter', time=t_last)
     convergence_rates = [errors[i + 1][1] / errors[i][1] for i in range(len(errors) - 1)]
     convergence_rate = convergence_rates[0]
     convergence_bound = alpha / (1 - alpha)