[beeswax] Query explain renders query Execute button useless after a page back

In the Hue 2.2.0 editor for Hive queries, actions:

• enter query
• click Explain will display the explanation, as expected
• click on Back (or Query, then Back), returns to query editor as expected
• click Execute takes you back to the explanation page, not execution
• clicking on Beeswax and starting over (query, execute) still works

This was using Firefox browser on Red Hat.