Service script to check the files in the repository

[Alexander Belchenko]

I need some service script to check the files in the repositories. I 
want to avoid using `bzr check` because it's too heavy for me. I have a 
lot of repositories on my trac server, and every week I make backup of 
it. I use the following check: collect `bzr list-branches` data and 
compare it with previous week data. If there is some branches missing 
then check if they were deleted by members of our team and not by disk 
crash or something.

I'd like to have some additional quick check just to be sure all files 
in the repository are present. I.e. for every repository I want to check 
that all names listed in pack-names are present in packs/ and indices/.
For packs/ I could check md5 as well, I think. For indices I guess I can 
only check that files aren't zero-length, or maybe I need open it with 
btree-dump just to see it has content that bzr can understand.

I don't need full `bzr check`, I need only the simple check as I 
described above. In all these years I use this setup I only sometimes 
had disk failures which results in converting long filenames of 
indices/packs into 8.3 form, and sometimes losing some branch/ 
directories. The latter is easy enough to recover using backup. I wish 
to extend my checks to cover the former case too.

Sometimes John posts snippets of code to work with repository 
structures. I'm not sure where I've seen it last time. Can you help me 
with the following part:

* open pack-names
* get the names of packs and indices
* simple check of indices content

Please?