We did this change recently:

  Name: Files-ul.154
  Time: 15 May 2016, 11:17:08.015805 pm
  
  - use #adoptInstance: to convert between binary and ascii mode instead of creating new collections

This assumes that we can convert a ByteString to a ByteArray using
Behavior>>adoptInstance. If the conversion does not work, as it the case
with a V3 image and Cog or interpreter VM, then we end up with a corrupt
image after trying to save the image as new version (and maybe other cases
as well).

It does not seem that #ascii and #binary are called frequently, even when
doing Monticello updates, so I suspect that the optimization is not very
important.

Do we need the #ascii and #binary optimizations in Files-ul.154?

Dave