CKAN version
2.9.5, probably others

Describe the bug
Updating an uploaded resource file through API does not update the resource's size field

Steps to reproduce
Steps to reproduce the behavior:

1. Create a dataset and a file upload resource
2. Observe the resource's size field value
3. Change the file through the UI
4. Observe the resource's size field value changes as it should
5. Use the action API to upload a new file with resource_patch (or resource_update, I assume)
6. Observe the resource's size field value stays the same

Expected behavior
The file size should reflect the uploaded file regardless of the method used to upload it

Additional details
I assume this is because the resource already has a size field when resource_update calls package_update, which assumes it is already set to the correct value. In resource_create the size is set, but resource_update just keeps the same value as before. Thus the new file size is not set.