fix ValueError exception on diff page

* lib/compat.py (cvs_strptime): make compatibility function throw a
    ValueError when time is not in expected format, so it is more
    like the native function

* lib/viewcvs.py (rcs_date_reformat): catch ValueError exception


git-svn-id: http://viewvc.tigris.org/svn/viewvc/trunk@702 8cb11bc2-c004-0410-86c3-e597b4017df7

lib/compat.py

@@ -57,7 +57,7 @@ else:
     if match:
       return tuple(map(int, match.groups())) + (0, 1, 0)
     else:
-      return None
+      raise ValueError('date is not in cvs format')
 
 #
 # os.makedirs() is new to Python 1.5.2

lib/viewcvs.py

@@ -2433,10 +2433,10 @@ def view_doc(request):
   fp.close()
 
 def rcsdiff_date_reformat(date_str):
-  date = compat.cvs_strptime(date_str)
-  if date:
-    return make_time_string(compat.timegm(date))
-  return date_str
+  try:
+    return compat.cvs_strptime(date_str)
+  except ValueError:
+    return date_str
 
 _re_extract_rev = re.compile(r'^[-+]+ [^\t]+\t([^\t]+)\t((\d+\.)*\d+)$')
 _re_extract_info = re.compile(r'@@ \-([0-9]+).*\+([0-9]+).*@@(.*)')