git.latest uses SSH_AUTH_SOCK instead of the defined identity

Description of Issue/Question

While using git.latest in a state combined with a specified identity git latest.uses my local SSH_AUTH_SOCK instead of the identity to clone the repo. This fails as my personal identity does not have read permissions to the repository.

Setup

git clone repo ABC:
  git.latest:
    - name: git@git.url.de:ABC
    - rev: master
    - branch: master
    - target: /opt/ABC/
    - submodules: True
    - identity: /root/.ssh/salt_git_deploy_key
    - require:
      - sls: setup.salt_git_deploy_key

Versions Report

salt-call --versions-report

Salt Version:
Salt: 2016.11.6

Dependency Versions:
cffi: Not Installed
cherrypy: Not Installed
dateutil: 2.2
docker-py: Not Installed
gitdb: Not Installed
gitpython: Not Installed
ioflo: Not Installed
Jinja2: 2.9.4
libgit2: Not Installed
libnacl: Not Installed
M2Crypto: Not Installed
Mako: Not Installed
msgpack-pure: Not Installed
msgpack-python: 0.4.2
mysql-python: Not Installed
pycparser: Not Installed
pycrypto: 2.6.1
pycryptodome: Not Installed
pygit2: Not Installed
Python: 2.7.9 (default, Jun 29 2016, 13:08:31)
python-gnupg: Not Installed
PyYAML: 3.11
PyZMQ: 14.4.0
RAET: Not Installed
smmap: Not Installed
timelib: Not Installed
Tornado: 4.2.1
ZMQ: 4.0.5

System Versions:
dist: debian 8.7
machine: x86_64
release: 4.4.79+523-ph
system: Linux
version: debian 8.7

Start at the git.latest state entry point and reproduce the supplied configuration with SSH_AUTH_SOCK set and identity pointing to /root/.ssh/salt_git_deploy_key. Trace which credential is used during the clone, then verify that the defined identity is honored and the repository can be cloned with the shown settings.