Upgrading to 2.1 removes linked condition from rule, resulting in activity -> email -> activity loop

Updating to 2.1 caused the linked condition (a field value comparison) in a rule to disappear. Since this rule was triggered by an activity being added and the activity was to send an email, any activity being added resulted in an email being sent. We theorize that one activity being added triggered an email, which recorded an activity, triggering another email, etc. A few thousand were sent before this was discovered (luckily, the email went to a staff member) and the rule disabled.

This also appears to have prevented activities from being recorded during this time.

On 5.3.1.