As we modify blueprint data we can end up with a situation where moving between releases leaves blueprints in a bad state and subsequently crashes on load:

thread 'ThreadId(1)' panicked at 'called `Option::unwrap()` on a `None` value', arrow2_convert-0.5.0/src/deserialize.rs:33

   0: backtrace::backtrace::trace
   1: backtrace::capture::Backtrace::new

Andreas fixed this while developing #3078 but we should back-port just the fix portion into 0.8.2 so that when we break things in 0.9.0 and users go back to 0.8.2 they don't get a crash.

This basically needs these three commits:

• 6773d88
• aab0806
• 814c0f6