publish_info file contains wrong data on partial respins

[Paride Legovini]

The .publish_info file published on cdimage together with the ISO images contains the serial of a given batch of images, e.g.:

http://cdimage.ubuntu.com/ubuntu-server/daily-live/pending/.publish_info

however the serial is wrong when only a subset of the images have been respun, while the others have just been copied over. This happens for example when a single architecture is respun.

The script generating the .publish_info file should keep track of which images are copied, and report their serial, or it should extract the serial from all the images every time:

  bsdtar -x -f image.iso -O './.disk/info'

which I think is easier to implement and probably more solid.