Cannot commit if 'push to default remote' is on and no remotes are defined

I've noticed in a few of my new repo creations lately, that my initial commit didn't do anything.

I also noticed that the checkbox under the commit message in the new-style UI is checked, but is greyed out, and says "push to (null)/master".

I have the General preference 'Push to default/origin remote when committing" turned on, and no remote defined on the repository I'm trying to commit to.

Resolving either of those issues (that is, unchecking the preference, or making a remote) allows me to commit.

However I believe this is a bug as I should be able to commit to a local repository which will never have any remotes, without unchecking that preference.

Please let me know if this is unclear!