Search & select user widget fails if request detail view is open

Activating the "search & select user" widget in the create request form fails if an existing request is already in view.

Steps to reproduce:
1. Go to Requests
2. Select any existing request from the results list to open the detail view pane
3. Click New
4. Click the search icon in the requester barcode field to activate the widget
5. An error message will appear: "operation GET on resource 'selUser' failed, saying: UserObject does not exist"

In addition, the console shows a 404 error on the resource http://localhost:9130/users/<request id>. Thus, the ID of the request currently in view is somehow being interpreted as a user ID to retrieve instead.