[boost] regex lib: bug with sets and back ref

Hello, The following behavior seems to be a bug: * regex '([a-c]+)\1' finds 'abcabc' at offset 0 in text 'abcabc' * regex '([abc]+)\1' finds 'bcbc' at offset 1 in text 'abcbc' * regex '([a-c]+)\1' finds nothing in text 'abcbc' ??? Can anybody confirm this? Tried both POSIX and Perl syntax/match mode. Ralph