--- a/tests/testlib/pythonpath.sh	Fri May 01 21:05:37 2020 +0200
+++ b/tests/testlib/pythonpath.sh	Thu Apr 09 14:49:31 2020 +0200
@@ -3,7 +3,7 @@
 export SRCDIR="`dirname $TESTDIR`"
 if [ -n "$PYTHONPATH" ]; then
     export HGTEST_ORIG_PYTHONPATH=$PYTHONPATH
-    if uname -o | grep -q Msys; then
+    if uname -o 2> /dev/null | grep -q Msys; then
         export PYTHONPATH="$SRCDIR;$PYTHONPATH"
     else
         export PYTHONPATH=$SRCDIR:$PYTHONPATH