Change "Http Transport returned a 0 status code" error to make it less annoying

Multiple scenarios when an action is done without waiting for an AJAX action to finish produces the error message Http Transport returned a 0 status code" :

Scenario 1

1. clic on the arrow to unfold a folder in the left tree
2. just after, clic on another folder in the left tree to navigate to it
3. the error message is displayed

Scenario 2

1. Take a folder with 20 documents
2. Select all documents in the content view
3. Unselect 3 documents
4. Without waiting for the selection to be finished, clic on the Copy button
5. the error message is displayed

For each scenario, it is easier to reproduce if the repository contains a lot of documents and the AJAX requests take a lot of time to run