Pull: create image record after blobs download

When pull image with unpack option, the fetch action will defer blobs
download until unpack. If create image record in ImageService before
blobs download, the following requests to use image will fail because
there is still missing blobs download.

In order to fix concurrent issue, need to create image record after
blobs download.

Fix: #3937

Signed-off-by: Wei Fu <fuweid89@gmail.com>

client.go

@@ -390,7 +390,11 @@ func (c *Client) Fetch(ctx context.Context, ref string, opts ...RemoteOpt) (imag
 	}
 	defer done(ctx)
 
-	return c.fetch(ctx, fetchCtx, ref, 0)
+	img, err := c.fetch(ctx, fetchCtx, ref, 0)
+	if err != nil {
+		return images.Image{}, err
+	}
+	return c.createNewImage(ctx, img)
 }
 
 // Push uploads the provided content to a remote resource