Index: tests/Makefile.am
===================================================================
--- tests/Makefile.am	(revision 4dd10fbd1d6b6cf437406603b466ce87ae7f2136)
+++ tests/Makefile.am	(revision 386fb57527e7266fbdf2a63a63fa7f20796e2991)
@@ -118,5 +118,5 @@
 
 all-local : # This name is important to automake and implies the default build target.
-	@+$(TEST_PY) --debug=$(debug) --install=$(installed) --archive-errors=$(archiveerrors) $(concurrent) $(timeouts) $(ARCH) --all # '@' => do not echo command (SILENT), '+' => allows recursive make from within python program
+	@+$(TEST_PY) --debug=$(debug) --install=$(installed) --invariant --archive-errors=$(archiveerrors) $(concurrent) $(timeouts) $(ARCH) --all # '@' => do not echo command (SILENT), '+' => allows recursive make from within python program
 
 install : all-local # PAB only