Copy data before compression to prevent 'file changed as we read it'
The backup Rake task used to suck data directly from the live data directory into the backup. Under many circumstances this worked OK. However, really active instances would experience a 'file changed as we read it' error - especially with data like the registry. This now copies the data first, then compresses it. It will take a bit more disk space while the backup is in progress, but it's a necessary thing.
Closes #26881 (closed)