Creating a new repo while on a custom domain takes you to bitbucket.org (BB-9357)

I'm experimenting setting up a custom domain for my projects, and when I click "Create" at the top of the page while on the custom domain, it redirects me to bitbucket.org, and doesn't redirect me back after the fact.

I notice that repository creation is https://, so presumably it's intentional that we're redirected to bitbucket.org during creation, but it'd be great if we were redirected back afterwards.

Related, but arguably not the same issue, going to http[s]://mycustomdomain/repo/create is a 404, rather than a HTTP redirect, and interestingly on this page the create URL doesn't point to bitbucket.org, it points to the custom domain (and also 404s).