--- a/tests/hghave	Tue Jun 05 00:20:53 2012 +0100
+++ b/tests/hghave	Sun Jun 10 16:32:22 2012 +0100
@@ -202,7 +202,7 @@
         os.rmdir(d)
 
 def has_pyflakes():
-    return matchoutput('echo "import re" 2>&1 | pyflakes',
+    return matchoutput("sh -c \"echo 'import re' 2>&1 | pyflakes\"",
                        r"<stdin>:1: 're' imported but unused",
                        True)
 
@@ -241,6 +241,8 @@
     return os.getenv('MSYSTEM')
 
 checks = {
+    "true": (lambda: True, "yak shaving"),
+    "false": (lambda: False, "nail clipper"),
     "baz": (has_baz, "GNU Arch baz client"),
     "bzr": (has_bzr, "Canonical's Bazaar client"),
     "bzr114": (has_bzr114, "Canonical's Bazaar client >= 1.14"),