InvalidProxyContract

[germartinez]

Situation locally / in Travis

The CPK tests uses the cpk-test branch of the Safe Relay Service, which has this conditions commented:
https://github.com/gnosis/safe-relay-service/blob/cpk-test/safe_relay_service/relay/services/transaction_service.py#L388

This is necessary because the apps are sharing the same Ganache instance and they need to deploy all the contracts needed.

Situation in production (checked on Rinkeby)

The CPK uses the Safe Relay Service in production and this exception is thrown:
https://github.com/gnosis/safe-relay-service/blob/master/safe_relay_service/relay/services/transaction_service.py#L392

The proxy contract deployed by the CPKFactory.sol should be recognized as valid by the Safe Relay Service because the official Safe contracts are used (https://github.com/gnosis/contract-proxy-kit/blob/master/contracts/CPKFactory.sol#L4-L5) but somehow is not taken as a valid one.