Don't reenter putChangeset, allow reuse of open changeset id
Don't reenter putChangeset, allow reuse of open changeset id

We are going to start trying an opportunistic save, then only
start the conflict resolution stuff if the server returns a 409.
Reusing an already open changeset makes sense in this situation.

AndreasHae/iD,kartta-labs/iD,openstreetmap/iD,mapmeld/iD,bagage/iD,AndreasHae/iD,digidem/iD,bagage/iD,bagage/iD,kartta-labs/iD,kartta-labs/iD,morray/iD,openstreetmap/iD,morray/iD,ngageoint/hootenanny-ui,mapmeld/iD,ngageoint/hootenanny-ui,digidem/iD,openstreetmap/iD,ngageoint/hootenanny-ui,mapmeld/iD,AndreasHae/iD