issue upgrading git from 1.8.2.1 to 2.8.0

Hi,

Last week we upgraded git from 1.8.2.1 to 2.8.0. We saw some very weird behavior where git clones and pushes were working, but git fetch was not.

Here is our setup:

We have 10+ nodes caching a few repositories, the repos were originally cloned via git 1.8.2.1 with `git clone --mirror <repo>`

We have 3000+ nodes that take deploys using the git protocol, via `git fetch`, the existing repositories were also cloned via git 1.8.2.1 from the caching nodes.

When we upgraded to 2.8.0, all nodes received the upgrade.

We observed that when we tried to deploy code to the nodes (they run `git fetch` to update the repository) this would fail.

The fix: we deleted the repositories originally cloned via git 1.8.2.1, and did a `git clone <repo>` dropping a fresh repository that was cloned using git 2.8.0. Everything started working correctly. Our running theory here is that there was some incompatibility with the repositories cloned with the old version of git, and trying to run `git fetch` with the newest version of git.

Thanks, Gennaro