Opening a running build from "toast" popup, and then closing, fails to load activity/branches tab data.

To reproduce: configure a multibranch job, then go to blue ocean and run a build off a branch (in the branch tab).

Click on the "open" link in the toast that pops up, which will give you a view of the executing build. If you then dismiss the modal, it will show an empty screen (no activity/branches listed).