I see the work around, and I have already implemented similar workarounds in my code. However, I have 2 problem with this response:

1. The behaviour changed. As the documentation did not explicitly say tarfile does not support unicode file paths, and it worked prior to 2.5, then I would say breaking that behaviour at the least calls for a documentation update.
2. The error message stamps from struct failing to pack a unicode string. First of all, I did not grasp the subtle message of it being a unicode string as opposed to a non-unicode string. You see, I actually did not expect unicode string in the first place, it was a by-product of TEXT_DATA from a DOM tree. I can understand why struct.pack() throws (because no explicit encoding scheme was specified) but it was so cryptic with regard to tarfile itself, that I had to modify tarfile to track down the reason for the exception.
In short, I would prefer the owner of tarfile to make an explicit support or not-supported call on unicode file path, document said decision and make more reasonable attempt in presenting releavant exceptions.
Thank you for looking into this.