[Bug]: Growup turns around unintentionally when landing on a slope

[Brockengespenst]

SuperTux Version

v0.6.3-1293-gd4d88e83d

System Information

macOs Ventura

Expected Behavior

Growup does not change direction when landing on a slope.

Actual Behavior

Growup changes direction when landing on a slope. Not always, but very often.

Steps To Reproduce Actual Behavior

1. Place bonus block above a slope
2. Hit the bonus block from below
3. Watch the growup landing on the slope

Additional Information

Watch this video: https://github.com/SuperTux/supertux/assets/155102424/b8fb00d8-8f30-49b6-94ed-8b0d3f550221

Guidelines For Reporting Issues

• [X] I have read https://github.com/SuperTux/supertux/blob/master/CONTRIBUTING.md#bug-reports.
• [X] I have verified this isn't an issue that's already been reported.
• [X] I have verified this isn't a discussion, or an issue about a crash or a feature request, but rather an actual bug ─ that is, the game did something not intended.
• [X] I have verified this issue is not about wrong translations (use Transifex for those), or anything unsupported (e.g. third-party add-ons).
• [X] In this report, I have only included details about one (1) bug.
• [X] If I make a mistake while submitting this report, I agree to use the "Edit" feature to correct it, instead of closing this issue and opening a new one.