cloud-images.ubuntu.com/releases points to non-existant files

[Scott Moser]

As shown in bug 1493102, cloud-images.ubuntu.com is advertising files
in simplestream data that it does not have.

The vast majority of these are from releases that are no longer supported.
Someone must have made the decision to remove this content from cloud-images.ubu
ntu.com. Such an example:
  http://cloud-images.ubuntu.com/releases/server/releases/quantal/
While the directories are there, each is empty.

# new instance (this one wily, shoudl be fine on trusty also)
$ sudo apt-get update
$ sudo apt-get install -qy simplestreams bzr make
$ bzr branch lp:simplestreams simplestreams
$ cd simplestreams
$ rm -Rf gnupg; make gnupg PUBKEYS=examples/keys/*.pub
$ ( ./tools/tenv hook-check-downloads http://cloud-images.ubuntu.com/releases/ 2>&1 ; echo $?; ) | tee out.log

$ grep BAD_URL out.log | wc -l
632

$ grep BAD_URL out.log | egrep -v "(lucid|oneiric|raring|quantal)" | wc -l
6

So, if we ignore the unsupported releases, we reduce the problematic urls from 6
32 to 6. The other 6 are alpha-1 and beta-2 builds of precise.

Please either publish the data, or fix the meta-data that points to this data.

[Scott Moser (smoser)]

The bug was filed as a result of inadvertant bad data on cloud-images.ubuntu.com.
They did not intend to delete the data, but moved it off cloud-images.ubuntu.com to elsewhere (and redirected there).

Thus, the problem is no longer present.
However, I added a commit that will allow us to skip unsupported releases in the future, as it does seem to make sense to avoid publication of metadata describing out of date releases.