gitdir is not supported

[byplayer]

newest git support gitidr in .git.
But egg does not support yet.

[byplayer]

it is in the changes of git 1.7.8

https://lkml.org/lkml/2011/12/2/316

When populating a new submodule directory with "git submodule init", the $GIT_DIR metainformation directory for submodules is created inside $GIT_DIR/modules// directory of the superproject and referenced via the gitfile mechanism. This is to make it possible to switch between commits in the superproject that has and does not have the submodule in the tree without re-cloning.

[bogolisk]

I believe the latest code support gitdir however I couldn't test thoroughly since I don't use submodule
some one please test