Fixed partial match bug:

The following program demonstrates what we believe is a bug in regex partial
match algorithm:

    int main()
    {
    //  boost::regex const re("(ab)?c"); // ok
        boost::regex const re("(ab)?"); // fails in the assert below

        boost::cmatch what;
        assert(boost::regex_match( "a", what, re, boost::match_default |
boost::match_partial ));
    }


[SVN r14110]

libs/regex

@@ -1 +1 @@
-Subproject commit b856079e7486ec7abac86accace9e11d9f3a58c0
+Subproject commit b2c4abc9cf6cc57103b23e4a136da0eacaa2779b