Factor out the core logic that merges people into a new method
Factor out the core logic that merges people into a new method

The post method was getting very long; this refactoring extracts into a
method the logic that alters the primary Person and linked objects.

DemocracyClub/yournextrepresentative,DemocracyClub/yournextrepresentative,DemocracyClub/yournextrepresentative