--- a/tests/test-filecache.py	Tue Sep 01 11:03:47 2020 -0400
+++ b/tests/test-filecache.py	Wed Nov 11 22:01:45 2020 +0100
@@ -5,7 +5,7 @@
 import sys
 
 if subprocess.call(
-    ['python', '%s/hghave' % os.environ['TESTDIR'], 'cacheable']
+    [sys.executable, '%s/hghave' % os.environ['TESTDIR'], 'cacheable']
 ):
     sys.exit(80)