[Regression] Retry of command with defer error: Could not find manifest in --state path

[gshank]

Current Behavior

Executing a "retry" command on a command with "defer" sees error: Could not find manifest in --state path

Expected Behavior

Retry command completes successfully

Steps to reproduce

Do a retry of a command with a "--defer" component.

Relevant log output

15:20:51 Encountered an error:
Runtime Error
Could not find manifest in --state path: "<dbt.contracts.state.PreviousState object at 0x112b56170>"

Additional context

This regression was caused by moving the "defer_state" parameter to global parameters. The existing code caused that flag to be instantiated as a "PosixPath('None')" object instead of Python None.