Upgrade git on Debian/Jessie

Align git to v2.11.x (Debian/Stretch version) on the
older Jessie version as well.

Change-Id: Ia5cc94542c89dd96e5f953a815af3231f285ba03
1 file changed
tree: 3ca08f8992208e0f941371a96b23064541c9ed21
  1. jenkins/
  2. jenkins-docker/
  3. worker/
  4. .gitignore