Oathbreaker: Signature spell not returned to command zone

[fearphage]

I'm not sure if this is specific to the Time Spiral spell or a general issue with spells that exile themselves on resolution, but once cast it goes into permanent exile.

Repro

1. Time Spiral as signature spell.
2. Cast Time Spiral and let the spell resolve.

Expected Result

Spell is returned to command zone... to allow it to be cast with appropriate commander tax.

Actual Result

Spell stays in permanent exile.

Here's a screenshot of the issue:

Notes

@LevelX2 previously worked on a fix for the oathbreaker format referencing spells not returning to the command zone in a recent ticket (#6695).

[fearphage]

@LevelX2 Looking at the code for the fix, it references the graveyard, battlefield, and now exile.

What about spells that would go to the library like Seasons Past?

[LevelX2]

@fearphage library and hand are already handled in the switch above because this is also done for normal commander cards.

[fearphage]

FYI this is a regression.