.gitlink for Summer of Code

I would like to tackle .gitlink for Summer of Code. The deadline is about a day away, but this is a chance to make sure you still think .gitlink is a good idea, and to see if there are any big problems with the idea in general (before a more detailed proposal is actually submitted).

.gitlink is for a lightweight checkout of a branch into a separate directory on the local filesystem. A .gitlink'ed checkout has its own index+HEAD, but otherwise refers back to the main repository for objects, refs, etc.

Junio has said (http://www.spinics.net/lists/git/msg24964.html) he works in a similar way with many work trees which are symlinked to his main repo: : gitster git.wk0; ls -l .git/ total 120 drwxrwsr-x 3 junio src 4096 Mar 5 16:22 ./ drwxrwsr-x 15 junio src 16384 Mar 5 16:23 ../ -rw-rw-r-- 1 junio src 41 Mar 5 16:22 HEAD lrwxrwxrwx 1 junio src 27 Mar 3 22:53 config -> /src/git/.git/config lrwxrwxrwx 1 junio src 26 Mar 3 22:53 hooks -> /src/git/.git/hooks/ -rw-rw-r-- 1 junio src 82455 Mar 5 16:22 index lrwxrwxrwx 1 junio src 25 Mar 3 22:53 info -> /src/git/.git/info/ drwxrwsr-x 3 junio src 4096 Mar 3 22:59 logs/ lrwxrwxrwx 1 junio src 28 Mar 3 22:53 objects -> /src/git/.git/objects/ lrwxrwxrwx 1 junio src 32 Mar 3 22:53 packed-refs -> /src/git/.git/packed-refs lrwxrwxrwx 1 junio src 25 Mar 3 22:53 refs -> /src/git/.git/refs/ lrwxrwxrwx 1 junio src 28 Mar 3 22:53 remotes -> /src/git/.git/remotes/ lrwxrwxrwx 1 junio src 29 Mar 3 22:53 rr-cache -> /src/git/.git/rr-cache/

A .gitlink could simplify this, ridding the directory of symlinks and instead having a .gitlink file that specifies a $GIT_DIR to which everything refers.

My implementation will be based on Josef Weidendorfer's "[RFC] Lightweight checkouts via ".gitlink"" (http://thread.gmane.org/gmane.comp.version-control.git/33755), which didn't receive much objection (or comment at all). Hopefully this doesn't mean you simply aren't interested.

Goals:
  o Lightweight checkouts are essentially branches that reside outside of the
    main repository on the local filesystem.
  o They act as normal git checkouts (i.e. git tools know about .gitlink)
  o They can be moved around and maintain their link to the base repo
  o They can exist within other checkouts (for eventual submodule support)
  o git-clone --light-weight option to set this up
  o porcelains (i.e. cogito) don't barf

Is this something that you would like to see?  Any other comments?

Thanks,

Eric