Purging old entries failed with wrong locale

If the locale is not en-US the entry purge operation failed :

2011-07-17 08:56:17,878 - denyfileutil: INFO purging entries older than: Sun Jun 19 08:56:17 2011
2011-07-17 08:56:17,965 - denyfileutil: WARNING Parse error -- Ignorning timestamp: Wed Jul 13 23:46:16 2011 for: # DenyHosts: Wed Jul 13 23:46:16 2011 | ALL: 95.171.5.77

2011-07-17 08:56:17,974 - denyfileutil: WARNING exception: a float is required
... (it continues for each entries)

I fixed the problem by writing the timestamp (in seconds) instead of a date/time string. Now it works perfectly on my computer.