When a generated file does alter but keep the file size the same, the previous script was not able
to catch the situation as only the file size was compared. The checksumming was not allowed by the
provider and the time-based approach was also not possible due to the recreation of all files by
Hugo.
The solution is to use a local copy of the upstream files with the same times as the upstream ones.
By using rsync's more advanced features, only the changed files are going to be rewritten therein.
As a result, the time-based approach now works again.
