Reassigned Assignments leads to incorrect Sandbox Urls

[bwreid]

What is happening?

It is possible to create a condition where the sandbox_url for an assignment is incorrectly pointing towards the wrong person's sandbox. This will only happen if multiple people are assigned to an article or someone is reviewing an article.

To Reproduce

• Article with title of AssignmentA is given to user with a username of "UsernameX"
• AssignmentA will have a sandbox_url with something like /User:UsernameX/AssignmentA
• Another user is given a review assignment (ReviewB) that reviews AssignmentA. The sandbox_url will be assigned to the existing sandbox_url
• AssignmentA is removed from "UsernameX" and assigned instead to "UsernameY"
• ReviewB still points to the "UsernameX" sandbox, not "UsernameY"

Expected behavior

The sandbox_url should be updated on reassignment. This could likely be done before an assignment is being deleted.

Additionally, if possible we should check to see if revisions already exist on the prior sandbox. If they do, we should not change the sandbox_url