I have had several tests in the last few days where test/format writes out an empty isolation config setting. Then if you copy/paste that CONFIG on a failure, the program fails.

It looks something like this:

...
internal_key_truncation=1
internal_page_max=16
isolation=
key_gap=13
...

We need to find/fix this so that the CONFIG printed out by the program on failure can be used as-is.