Holdout settlement cannot pay coloured mana when paying for a cost.

If you have Holdout Settlement and an untapped creature onboard, you can use Holdout Settlement to tap the creature and add a coloured mana pip to your mana pool if you aren't in the process of paying a cost.

However, if you cast a spell, then click Holdout Settlement, it only treats it as paying < C > from the cost. It doesn't give you the option to tap a creature to pay a coloured mana pip instead.

**I do have the flag set that doesn't show me choices if there is only one option** Probably not relevant, but just in case.

Reproduce the issue by using Holdout Settlement to pay a spell cost while an untapped creature is onboard, then inspect the mana-payment and Holdout Settlement implementations. Compare payment outside and during cost payment; done means the coloured mana option is available when appropriate, with regression coverage for the reported scenario.

Written by the indexing model from the issue text.