--- a/tests/testlib/pythonpath.sh	Wed Apr 08 01:17:01 2020 +0800
+++ b/tests/testlib/pythonpath.sh	Fri May 08 22:50:09 2020 +0800
@@ -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