To reproduce this:

* Go to the all builds page
* Apply any filter (for example, "Builds with errors" from the Errors column)
* Hover over a different filter button (for example, the one in the "Failed tasks" column)

There is a title attribute added to that filter button. The title attribute should only be created for the applied filter button (i.e. the one with the btn-primary class), in the above example, the one in the Errors heading.