Truffle Testing – Why Does a Passing Test Fail on Testrpc?

Using Truffle and testing against both Truffle's own blockchain and against testrpc yields different results.

I am trying to test that my deployed contract is setting its owner correctly (owner being set to msg.sender in the constructor)

contract Cocktail {
  address public owner;

  function Cocktail() public {
    owner = msg.sender;
  }
}

My Migration script is like

module.exports = (deployer, network, accounts) => {
  const superuser = accounts[0]
  console.log('Deploying to network', network, 'from', superuser)

  deployer.then(() => Cocktail.new({ from: superuser })).then((cocktail) => {
    console.log('Deployed Cocktail with address', cocktail.address)
  })
}

My test is like

const Cocktail = artifacts.require('./Cocktail.sol')

contract('Cocktail', (accounts) => {
  const superuser = accounts[0]

  it('is owned by superuser', () => Cocktail.deployed()
    .then(instance => instance.owner())
    .then((owner) => {
      assert.equal(owner, superuser, `Expected the owner to be '${superuser}'`)
    }))
})

If I just use Truffle's own blockchain and run truffle develop then compile, migrate, then test it's all good.

Contract: Cocktail
  ✓ is owned by superuser

If I fire up testrpc and run truffle test however it claims to migrate okay but the test fails:

Using network 'development'.

Deploying to network development from 0x9aa5b3cee03060172ec9968a49857c2a68341f67
Deployed Cocktail with address 0x2294c2ef0db6994cf0c5a777e10e5be5e7aab69b

  Contract: Cocktail
    1) is owned by superuser
    > No events were emitted

  0 passing (86ms)
  1 failing

  1) Contract: Cocktail is owned by superuser:
     Error: Cocktail has not been deployed to detected network (network/artifact mismatch)

What is going on?