Sitefinity 4.1 problem uploading images with admin tools

We suddenly encountered an issue when uploading images using the Sitefinity 4.1 back-end admin tools. Now suddenly, when the content creators attempted to upload an image, they were suddenly getting a 404 error with the message:

Please review the following URL and make sure that it is spelled correctly.
Requested URL:
/Telerik.Sitefinity.AsyncImageUploadHandler.ashx

...Of course this functionality worked just fine in the development environment. The entire site was republished to staging, but they still were experiencing this issue of not being able to locate AsyncImageUploadHandler.ashx.

After examining everything, it ends up that there were several new httphandlers added in the system.webServer section in the local web.config that needed to be added to the staging site's config, specifically in this case the missing offender was:

<add name="Telerik.Sitefinity.AsyncImageUploadHandler" path="Telerik.Sitefinity.AsyncImageUploadHandler.ashx" verb="*" type="Telerik.Sitefinity.Modules.Libraries.Web.AsyncImageUploadHandler, Telerik.Sitefinity" />

I assume these settings were added when we upgraded to 4.1, SP1. According to the upgrade instructions, upgrading locally and then publishing everything except the Sitefinity configuration files to staging will automagically update the remote site to SP1. But you also need to make sure to merge the updates to your web.config as well.