Pipelines tab grows in size if selected after changes tab

In a merge request page if you click on the "pipelines" tab, then switch to the "changes" tab (with side-by-side diff selected), then switch back to "pipelines", you'll notice that the pipelines table is no longer constrained by the fixed CSS width.

This was tested in Safari 10 on GitLab.com running GitLab 9.0.0-rc2