--- a/client.py
+++ b/client.py
@@ -1,10 +1,13 @@
 #!/usr/bin/env python
 
+# Warning, this file must be compatible with Python 2.4, for our
+# various tools, such as http://mxr.mozilla.org/ see-also: Bug 601207
+
 # Repo Defaults
 # 'REV' controls the default rev for All the various repo's
 # Define x_REV to override. Where x can be one of:
 #  "COMM", "MOZILLA", "CHATZILLA", "INSPECTOR" or "VENKMAN"
 DEFAULTS = {
   # Global Default Revision
   'REV': "default",
 
@@ -56,17 +59,17 @@ SWITCH_MOZILLA_REPO_REPLACE = '%s://hg.m
 SWITCH_MOZILLA_BASE_REV = "GECKO_1_9_1_BASE"
 
 import sys
 # Test Python Version. 2.4 required for `import subprocess`
 pyver = sys.version_info
 if pyver[0] <= 1 or (pyver[0] == 2 and pyver[1] < 4):
   sys.exit("ERROR: Python 2.4 or newer required")
 elif pyver[0] >= 3:
-  sys.exit("ERROR: Python series 3 is not supported, use series 2 > 2.4")
+  sys.exit("ERROR: Python series 3 is not supported, use series 2 >= 2.4")
 del pyver
 
 import os
 import datetime
 from optparse import OptionParser, OptionValueError
 
 topsrcdir = os.path.dirname(__file__)
 if topsrcdir == '':