Now there is a good way of using Dropbox as a true Git remote: git-remote-dropbox.

Anish Athalye

git-remote-dropbox is a Git remote helper that enables using Dropbox as a true, safe Git remote. The common approach of storing a bare Git repository in a Dropbox-synced folder is unreliable because Dropbox doesn't maintain atomicity for Git operations, leading to repository corruption. git-remote-dropbox solves this by acting as a transparent bidirectional bridge between Git and Dropbox, preserving all the consistency guarantees of a traditional Git remote. It supports standard Git commands (clone, pull, push) and works safely with shared Dropbox folders, enabling collaboration with unlimited private repos.