Try:
git config --global push.default current
It should avoid the kind of error message mentioned here
error: failed to push some refs to 'git@github.com:jkubicek/my_proj.git'
hint: Updates were rejected because a pushed branch tip is behind its remote
hint: counterpart. If you did not intend to push that branch, you may want to
hint: specify branches to push or set the 'push.default' configuration
hint: variable to 'current' or 'upstream' to push only the current branch