tr1:regex has different behavior between vs2008 and vs2010 on some regular expression by Semlex

Hi ,
As described here : http://social.msdn.microsoft.com/Forums/en-US/vclanguage/thread/d3d5ead8-f5a3-4b59-9d7b-5ba8c4f0ef01
I noticed a different behavior on some regular expressions betsween vs2008 sp1 and vs 2010.

With the following small test case :
const char *test = "TESTONE<TESTTWO<<TESTTHREE<TESTFOUR<<<";
char buf[4000];
memset(buf,0,4000);
std::string l_fmt("");
std::tr1::regex l_regular_expression;                    
l_regular_expression =

"^(([A-Z])|([A-Z]<[A-Z])){1,50}<<";


std::tr1::regex_constants::match_flag_type fonly = std::tr1::regex_constants::format_first_only;
*std::tr1::regex_replace(buf,
        test,
         test + strlen(test) ,
        l_regular_expression,l_fmt,fonly) = '\0';

in vs 20008 buf will contain :
TESTTHREE<TESTFOUR<<<
in vs 2010 buff will contain
TESTONE<TESTTWO<<TESTTHREE<TESTFOUR<<< , so that nothing is replaced.

Could anybody explain me which one is right

Regards ,

Sasha