Something seems broken on azure/azure sdk side - it is currently not
possible to copy a blob of type AppendBlob using `CopyFromURL`.
Using the AppendBlob client via NewAppendBlobClient does not work
either.
According to Azure the correct way to do this is by using
StartCopyFromURL. Because this is an async operation, we need to do
polling ourselves. A simple backoff mechanism is used, where during each
iteration, the configured delay is multiplied by the retry number.
Also introduces two new config options for the Azure driver:
copy_status_poll_max_retry, and copy_status_poll_delay.
Signed-off-by: Flavian Missi <fmissi@redhat.com>
2b72c4d1ca