File change notification issue on XDrive

File change notifications aren't working properly currently when the file system is on xdrive. Due to the issues, we will receive change notifications for create/delete/modify file operations but the WatcherChangeTypes we receive will always be Changed. Therefore, we can't use the change type to distinguish between deletes, creates, etc.

In some cases we've worked around this already (see https://github.com/Azure/azure-functions-host/pull/3441). However there are other places that haven't been fixed yet where we're using the change type to make decisions, e.g. here: https://github.com/Azure/azure-functions-host/blob/b5c21a9000e35cf87069f55da0c808af70ca1d60/src/WebJobs.Script.WebHost/FileMonitoringService.cs#L147.

Start with src/WebJobs.Script.WebHost/FileMonitoringService.cs around line 147 and inspect how WatcherChangeTypes drives decisions. Compare the existing workaround in pull request 3441, then locate other affected uses. Done means create, delete, and modify notifications on xdrive are handled correctly rather than all being treated as Changed.

Written by the indexing model from the issue text.