Before deleting a repository index generation file, BlobStoreRepository
checks for the existence of the file and then deletes it. We can save
a request here by using BlobContainer.deleteBlobIgnoringIfNotExists()
which ignores error when deleting a file that does not exist.
Since there is no way with S3 to know if a non versioned file existed
before being deleted, this pull request also changes S3BlobContainer so
that it now implements deleteBlobIgnoringIfNotExists(). It will now save
one more request (blobExist?) when appropriate. The tests and fixture
have been modified to conform the S3 API that always returns a 204/NO
CONTENT HTTP response on deletions.
8fa06294ab