Error paginating after new comment insertion

[johnnyoshika]

When paginating after a new comment is inserted, and when the newly inserted comment returns from the server through pagination, this results in an ID conflict:

This also results in a duplicate comment, even through they have the same ID.

To reproduce:

• Insert a new comment
• Keep clicking More Comments until the newly inserted comment appears a second time

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This issue was highlighted in this PR: the-road-to-graphql/react-graphql-github-apollo#29