git keeps recreating packs, exploding backup increments

Hi,

I'm trying to understand git's repacking behaviour, as the observed behaviour doesn't match how I read the documentation or the code.

The problem we see is excessive backup increments for developer directories. The cause is that pack files keep getting regenerated for large repositories.

Users are not running 'git gc' manually, so the assumption is that this is caused by 'git gc --auto' being run implicitly.

 From what I can see in the code, and the documentation, it should only 
pack up objects not already found in existing packs. Or at the very 
least, not the objects found in the largest existing pack.

(at least not until gc.autoPackLimit is hit)

But this isn't happening. Old packs are constantly being replaced by new ones. Despite most of the objects being old and stable.

We tried gc.bigPackThreshold in the hope it would force it to reuse packs better. But all we got instead was duplication. It still creates new packs with everything. It just stopped removing the old ones.

Some guidance would be appreciated. I cannot find anything in the code or documentation that explains the current behaviour.

Regads,