git clone ignores GIT_ALTERNATE_OBJECT_DIRECTORIES

When running git clone, it seems that GIT_ALTERNATE_OBJECT_DIRECTORIES is
not considered. Even though most of the needed objects are in
GIT_ALTERNATE_OBJECT_DIRECTORIES, I still wind up with a ton of traffic over
the network and a huge .git/objects hierarchy.

Running "git gc" later pares down the .git/objects to a more reasonable
size, so it seems the problem is limited to git clone. Using "git clone
--reference" also seems to do the right thing.

Is this behavior intentional for some good reason I've overlooked, or have I
stumbled on a bug?

-- 
Brian Ristuccia
brian@ristuccia.com