XO still bootable with incomplete fs-update

[James Cameron]

No, fs-update was not modified for this.

zhashfs in olpc-os-builder was modified to place the zero block last in
the .zd file.  This would have worked in your favour.

We found that erase commands sent to certain microSD cards would fail.
We removed the erase commands from the start of fs-update.  This would
have worked against you.

You might modify zhashfs further to write an empty zero block first,
then write the remaining blocks, then write the real zero block.

What you are seeing is the re-use of the previous installation's
partition table against the new installation.

-- 
James Cameron
http://quozl.linux.org.au/