You're using an unsupported version of the host OS (Ubuntu 14.04) for this Yocto version (1.4) and it has newer versions of base tools (such as tar, giving you that problem right now), so things will fail.
I have tried fix things for 14.04 to work, but I ditched the idea after I fixed two and got the third one, which was a bit too enigmatic for mee to have an interest in fixing that.
After that I went with supported OpenSUSE 12.3 (which still requires one fix) and tried the recommended Ubuntu 12.04 (which works fine right away). So the real fix I'd recommend to you is changing your build host to Ubuntu 12.04 64-bit and you shouldn't have any building problems for a vanilla image.