fix pytest issue41: re-run tests on all file changes, not just

randomly select ones like .py/.c.

xdist/looponfail.py

@@ -188,7 +188,7 @@ class StatRecorder:
         self.check() # snapshot state
 
     def fil(self, p):
-        return p.ext in ('.py', '.txt', '.c', '.h')
+        return True  # we are sensitive to all file changes since 1.9
     def rec(self, p):
         return p.check(dotfile=0)