Hello,

First of all, thank you for this great crate!

Long story short, after reading sparse.tar into memory(Vec<u8>), the assertions are passing..
..but after writing these entries using append() method to the "output" Vec<u8> the same assertions fails.

I did fork the repository and the specific commit/test can be found here.

I couldn't find any example/testcase to pinpoint on how to work with sparse chunks, especially with extended sparse, so any help would be appreciated.