`cylc vr` bug with `initial cycle point = now`

[hjoliver]

[scheduling]
    initial cycle point = now
    [[graph]]
        PT1M = "foo"
[runtime]
    [[foo]]

1. cylc vip bug
2. cylc stop bug
3. (add a comment to flow.cylc)
4. cylc vr bug

Result:

ERROR - Workflow shutting down - InputError: option --icp is not valid for restart

This only happens for initial cycle point = now 🤔

[wxtim]

Duplicated, and assured myself that this is a VR bug - doing this serially as cylc install and then cylc play is fine.

[wxtim]

The problem is that the validate step alters the options object passed to it by storing the value of now as options.icp.

I can fix this problem (and any others like it) by copying the options passed to validate, but I wonder if I should stop validate changing options and check that it's not doing this elsewhere?