See what's changed is broken for Ruby two-fer

[ErikSchierboom]

Clicking on the "See what's changed" on my Ruby two-fer solutions gives me:

[angelikatyborska]

I got the same for my Elixir Bob.

[iHiD]

:+1:

Note to self: Needs this running once the DB has less going on:

 UPDATE `solutions` INNER JOIN `exercises` ON `exercises`.`id` = `solutions`.`exercise_id` SET solutions.git_slug = exercises.slug,            solutions.git_sha = exercises.git_sha,            solutions.git_important_files_hash = exercises.git_important_files_hash;

[iHiD]

@angelikatyborska @ErikSchierboom I think this should be fixed. Please reopen if it's not.