Fix up some flaky behavior of the new improved update e2e test.

No -- this'll only be set for the run of this script.  Users aren't going to "source" this so it won't leak outside the script.

The problem was that this needs to be set and passed down to child processes.  that is what `export` does.  I missed this as I already had it exported in the parent bash environment so it got passed down that way.