2.3.9

• Run git remote prune origin to remove possible branch name collisions before fetching.
• Update git fetch command to use + for heads and not just tags. From the git docs: "If the optional plus + is used, the local ref is updated even if it does not result in a fast-forward update."
• Deploy hook configuration config.input_ref and config.deployed_by now have defaults and won't NoMethodError when a value isn't set.
• Sets ServerAliveInterval=60 on ssh connections between servers to avoid timeouts on slow processes (esp. assets).
• Fix for rollback action ignoring ey.yml configurations. ey.yml is now loaded on rollback as intended.
• Explicitly use current ruby to syntax check deploy hooks.