Preserve uninitialized page scratch in range decoding

Author: danking

encodings/pco/src/take.rs

@@ -686,7 +686,10 @@ fn stream_range<T: Number + NativePType>(
                 decoder.read_into(chunk_id, chunk.as_slice(), n, buffer.as_slice(), output)?;
             } else {
                 if scratch.len() < n {
-                    scratch.push_n(T::default(), n - scratch.len());
+                    scratch.reserve(n - scratch.len());
+                    unsafe {
+                        scratch.set_len(n);
+                    }
                 }
                 decoder.read_into(
                     chunk_id,