Last mile for 1.0 again

LT> ..., but please don't LT> change that, since that would be yet another incompatible pack format LT> change, and I'd like to calm things down.

Calming things down is good. Some stuff we should be looking at during calming down period are:

 - Ask expert help to verify our use of zlib is OK; Linus asked
   for this in a message tonight.  I am not qualified to do this
   myself.

 - There is currently nothing that verifies the SHA1 sums
   embedded in idx and pack files.  A tool for it is needed
   [*1*].  I may be doing this myself.

 - Although there is a hook in sha1_file() that allows mapping a
   pack file on demand (and keep track of their uses for LRU
   eviction), there is currently no code to actually evict a
   mapped pack file.  We need to add some sort of use-reference
   counting to lock down a pack file in use, if somebody is
   inclined to do this.  I will not be doing this myself
   immediately.

 - Think about what to do with the "dumb server" pull protocols
   regarding packed archive files (think about http-pull).  I
   will not be doing this myself.

 - Design "smart server" pull/push pair.  This can independently
   and actively be done without impacting "calming down" period,
   and I am assuming Dan is already looking into this.  This may
   result in another "deathmatch" between Dan and Jason
   Mcmullan, which would be fun to watch ;-).

Not limited to "calming down the packed GIT", but bigger picture pre-release preparation items I think we need to look into are:

 - Update "Last mile for 1.0" list.  I think the only thing that
   is left from the one I posted on Jun 5th is the tutorials.

   Anybody interested in adding more pages to the tutorials?  If
   there is no taker, I may start continuing what is already
   there, stealing example project outline from "Arch meets
   Hello World" [*2*].

 - Double check the documentation, usage strings in the code and
   what the code does still match.  Last time I checked, I think
   some files in Documentation/ directory were not reachable
   from the main GIT(1) page and were not touched by the build
   process from Documentation/Makefile.  I will not be doing
   this myself.

 - Blame/Annotate.  Does anybody have a fast and correct one
   [*3*]?

 - Publicity.  Somebody may want to start preparing materials to
   have us included in http://better-scm.berlios.de/comparison/

[Footnotes]

*1* One possibility is to add that to fsck-cache when --full is used, but I am somewhat reluctant to do it that way. It would require you to place that "suspicious" pack under your repository's .git/objects/pack in order to verify it, which can spread the damage before you know it.

In general, idx file is relatively small, so we _could_ check the SHA1 sum for idx files when we map them at runtime in check_packed_git_idx(). However, verifying 1MB (kernel archive case) idx file every time we run a single core GIT command may be a price we would not want to pay, so I am not too enthusiastic about doing it. We certainly would not want to do this for pack files every time a pack is mapped at runtime (60MB kernel archive case).

*2* http://regexps.srparish.net/www/tutorial/html/arch.html.

I am not talking about stealing the concepts but just talking about stealing the sample project on which example players work in the sample sessions. I think its section on update/replay matches closely to merge/rebase, for example.

*3* I have what I wrote in Perl which does rename/copy/rewrite and multiple parents correctly, but it is way too slow for on-demand use.