+Clones a repository into a newly created directory. All remote
+branch heads are copied under `$GIT_DIR/refs/heads/`, except
+that the remote `master` is also copied to `origin` branch.
+
+In addition, `$GIT_DIR/remotes/origin` file is set up to have
+this line:
+
+ Pull: master:origin
+
+This is to help the typical workflow of working off of the
+remote `master` branch. Every time `git pull` without argument
+is run, the progress on the remote `master` branch is tracked by
+copying it into the local `origin` branch, and merged into the
+branch you are currently working on. Remote branches other than
+`master` are also added there to be tracked.
+