Summary: Currently, we use a symlink. Under git bash, it tries to run the symlink. This is not a recipe for success. Instead, use a trivial wrapper script.
Test Plan: Ran "arc" from git bash.
Reviewers: Makinde, btrahan, Koolvin
Reviewed By: Koolvin
CC: aran, epriestley
Maniphest Tasks: T124
Differential Revision: https://secure.phabricator.com/D1939