Long commit messages overflow viewport in file tree

With the update to 8.12.0 the file tree overflows the viewport if the message of the last commit in its head is too long. With 8.11.x it was truncated correctly. It seems the style for truncating the text is based on the length of the text itself, not of its surrounding table cell.

This behavior was reproducable in Chrome 53, Firefox 43, Internet Explorer 11, Edge 25. All on Windows 10.

I certainly hope the screenshot helps with this. If not just ask me :)