pkg/v1/mutate.Time sets all timestamps in an image to the given time, typically to make the image more reproducible. For timestamps in layers, it calls layerTime which reads the layer contents and writes them to a buffered tar.Writer. This means that if the layer is huge, we may run out of memory buffering its contents.

We should consider making this a lazy transformation, so that layer mutations aren't made until they're read. We did a similar thing in pkg/v1/cache, where layer contents aren't cached until they're read via Compressed or Uncompressed.