As far as I can tell, if a commented line on ipsec.conf ends with "\" then the following line will also be considered a comment (if the next line also ends with "\" the commenting is propagated). For example
#ike esp from A.A.A.A to C.C.C.C \ ike esp from A.A.A.A to B.B.B.B \ srcid foo.example.com dstid bar.example.com is treated as a commented block, instead of setting up a tunnel from A.A.A.A to B.B.B.B. I find this a bit surprising... What should be fixed: the parser, ipsec.conf.5 or my expectations? All the best Zé --