Jobs waiting conflict when leaving the page during an action

I'm not very sure of this issue's title so someone will need to see if this issue contains multiple problems.

Steps:

• Go to Sandbox.TestPage2
• Choose 'Delete' from the content menu
• Press the 'Delete' button in the first screen, go to the other screen. The generated URL will be for example

  http://localhost:8080/xwiki/bin/view/Sandbox/TestPage2?xpage=delete&jobId=refactoring/delete/1496157885928-940
  

• Now I pressed the browser's 'Back' button. The idea was that the user changed his mind.
• I repress the 'Delete' button again, it will generate another jobId, example:

  http://localhost:8080/xwiki/bin/view/Sandbox/TestPage2?xpage=delete&jobId=refactoring/delete/1496157979700-478
  

  Here we could have an improvement and try to provide the same jobId, since the it's the same user and the same page; or add a job timeout; etc. The problem is that from the Browser I cannot go back to the initial page and find the initial jobId.

• Then I go to another page TestPage3 and after a successful delete I try to Restore the page - the job gets frozen
• I go to the TestPage1 and try to Delete it, the job gets frozen

In order to restore the jobs you need to restart the server.

So maybe the problem is the usage of browser features like the 'back' button and having multiple jobs in different browser tabs, but I consider this usage to be a pretty common one. Maybe we can improve something.

See steps.gif