Prompt changes even if env doesn't exist.

[raistael]

Expected behavior: Prompt should remain unchanged and reject the action entirely. Actual behavior: Prompt prefix changes, despite the message of an env not existing. Reproduce: Activate an env that you know exists. Then attempt to activate one that doesn't exist.

I discovered by mistake that the bug exists when using a system I didn't setup. It doesn't appear to have changed any actual behavior, but the only way to correct the prompt is to deactivate and reactivate the desired target env.