Better handling variable length extended log data

[GoogleCodeExporter]

I ran into an issue where I was parsing nginx access logs that could have a
variable number of fields depending on the number of upstream proxies. 

The simple fix below should handle this case and be backwards compatible.

167         self._pattern = '^' + ' '.join(subpatterns) + '(.*)$'

Original issue reported on code.google.com by nathan.folkman on 18 Jan 2009 at 2:37