I used this plugin for a migration yesterday and although it was working okay in a test migration, now on the live site it’s failing. 
They are all md5 hashes but the console shows a problem with BCrypt:
BCrypt::Errors::InvalidHash (invalid hash)
/var/www/discourse/plugins/discourse-migratepassword/gems/2.3.1/gems/bcrypt-3.1.3/lib/bcrypt/password.rb:60:in `initialize'
Can I disable the use of this gem as I don’t need it? I commented out all lines in plugin.rb that my migration won’t need but that seems to have no effect, the error remains. 