Fixes #4387: Upgrade rudder-server-root 2.9.1 to 2.9.2 fails on rudder-agent on Ubuntu 12.04 LTS
Merge pull request #462 from jooooooon/bug_4387/upgrade_rudder_server_root_2_9_1_to_2_9_2_fails_on_rudder_agent_on_ubuntu_12_04_lts

Fixes #4387: Don't fail on rudder-agent stop, force stop if necessary