tcp match --syn option and FIN flag

[Pascal Hambourg <pascal.mail@xxxxxxxxxxxxxxx>]

Hello,

Found in iptables 1.3.2 changelog :

- Include FIN bit in mask of "--syn" bits

With this change a TCP packet must have the FIN flag cleared in order to 
match the --syn option, while it was not necessary with previous 
iptables versions.
Why ? Isn't the SYN flag supposed to have precedence over the FIN flag, 
so shouldn't FIN be ignored when SYN is set ?
Besides, this change has been applied only to libipt_tcp.c, not to 
libip6t_tcp.c. Is there a reason to this ?

Thanks for your attention.