testsuite: Fix import on python 3.10

(cherry picked from commit 81a8f7a7daeb87db53d598ced4b303f8f320442f)

1 files changed, 2 insertions, 1 deletions

diff --git a/testsuite/driver/testlib.py b/testsuite/driver/testlib.py
index aa4a4138b8..26102772de 100644
--- a/testsuite/driver/testlib.py
+++ b/testsuite/driver/testlib.py
@@ -16,6 +16,7 @@ import sys
 from math import ceil, trunc, floor, log
 from pathlib import Path, PurePath
 import collections
+import collections.abc
 import subprocess
 
 from testglobals import config, ghc_env, default_testopts, brokens, t, \
@@ -852,7 +853,7 @@ def join_normalisers(*a):
         Taken from http://stackoverflow.com/a/2158532/946226
         """
         for el in l:
-            if (isinstance(el, collections.Iterable)
+            if (isinstance(el, collections.abc.Iterable)
                 and not isinstance(el, (bytes, str))):
                 for sub in flatten(el):
                     yield sub