chunked: drop special handling for "< 64" ranges

Avoid handling cases where the server doesn't support at least 64
ranges in a request, in order to prevent falling back to the
traditional pull mechanism.

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

pkg/chunked/storage_linux.go

@@ -947,11 +947,9 @@ func (c *chunkedDiffer) retrieveMissingFiles(stream ImageSourceSeekable, dirfd i
 		}
 
 		if _, ok := err.(ErrBadRequest); ok {
-			// If the server cannot handle at least 64 chunks in a single request, just give up.
-			if len(chunksToRequest) < 64 {
+			if len(chunksToRequest) == 1 {
 				return err
 			}
-
 			// Merge more chunks to request
 			missingParts = mergeMissingChunks(missingParts, len(chunksToRequest)/2)
 			calculateChunksToRequest()