Folding is sometimes wrong

[USSiamaboat]

Folding sometimes results in obviously invalid results like isolated islands.

I don't know how to reproduce this yet. It only happens occasionally when folding a paper with many layers.

[USSiamaboat]

Attempted fix with 4bb833d. Qualitative inspection shows that issues are less common, but they still appear at non-negligible frequencies when filtering for "hard" samples.

[USSiamaboat]

Previous testing was with an incorrect version. Haven't found any issues with the current version yet.
Will close this issue if I don't find any issues this week.

[USSiamaboat]

No issues found so far, closing for now