Fmirror util (net-misc/fmirror) don`t support files size larger than 2Gb.
22:13:34 : 150 Opening BINARY mode data connection for develop-0.tar (3961681920 bytes) 22:13:34 Getting file 'develop-0.tar' size = 2147483647
guessing it needs -DLARGE_FILE Or the equiv...let me ask someone who knows more than I :)
ok I tried to fix this in -r2, give it a shot.