The Clar test framework has a bug whereby it skips the parsing phase
on files with mtime=0.

Reported upstream at <https://github.com/vmg/clar/pull/78>.

diff --git a/tests/generate.py b/tests/generate.py
index b639c8f..111ca41 100644
--- a/tests/generate.py
+++ b/tests/generate.py
@@ -63,3 +63,3 @@ class Module(object):
 
-        self.mtime = 0
+        self.mtime = None # Guix sets all file mtimes to '0'
         self.enabled = True