DateUtil cannot parse date format 'Mon, 04 Aug 2014 01:08:21GMT'

[pprun]

com.ning.http.util.DateUtil$DateParseException: Unable to parse the date Mon, 04 Aug 2014 01:08:21GMT
at com.ning.http.util.DateUtil.parseDate(DateUtil.java:176)
at com.ning.http.util.DateUtil.parseDate(DateUtil.java:104)

Although it works with 'Mon, 04 Aug 2014 01:08:21 GMT' (blank char before GMT), some servers do return this format.