Meaningless activity records generated for inherited memberships whenever UpdateMembershipRecord script is run

Problem
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When UpdateMembership runs, say once a day, it deals with update of inherited memberships by deleting from civicrm_member all inherited memberships, then regenerates them from contact relationships. Each regenerated inherited membership registers a Membership Signup activity in civicrm_activity, even when there is no change in membership or relationship. The database quickly fills with these meaningless activities, making it difficult to use.

Solution
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UpdateMembershipRecord already passes a createActivity parameter telling civicrm_contact_membership_create to create an activity record WHEN membership status has changed. Modify the code which handles inherited membership to pay attention to this flag. Desired behavior is that activities are ALSO only created for inherited memberships when their "parent's" membership status has been changed.