This case brings up interesting developer coordination issues and illustrates the importance of a well-defined testing process as client developers prepare to implement changes affecting mainnet.
In this planned activation of changes on Ropsten testnet, when the forking block was reached, there was not enough mining power from Ropsten clients implementing Constantinpole changes. This led to a disorderly forking in which the intended upgraded network failed to quickly materialize / become dominant.
Additionally, a consensus bug was found, leading to a secondary fork (a more dire state of affairs which must be avoided at all costs on mainnet).
The result is that the Ropsten network, for lack of a better word, is shattered.
The situation is currently being discussed, investigated, and resolved in the AllCoreDevs gitter channel.