For the etcd client, amend AddMember() to handle a very
rare bug when multiple members can end up with the same
name. Match the member peer address and assign it the name of
the member we are adding. For the rest of the members with missing
names use their member IDs as name. The etcd node is not disrupted
by the unknown names.
The important aspects are:
- The number of members of the initial cluster must match
the members in the cluster.
- The member we are current adding is present in the initial cluster.
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