It's as simple as I'm trying to push to remote a branch called
git push origin v1
[new-branch] v1 -> master
v1 -> v1
git push origin v1:refs/heads/v1 will create the remote branch for you. The left side of the colon is the local branch, the right side is the remote branch. If the right side doesn't exist, it will be created. After that, you may want to use
git branch -u as suggested by Tim to set the upstream tracking info correctly.