Pitch take envelope: Slow start and slow end incorrect realtime spectral peaks

[juliansader]

When drawing a take pitch envelope, the take's spectral peaks adjust in real-time.

However, slow start and slow end curves do not adjust the colors correctly, as illustrated in the image below. From left to right, the curves are slow start / slow end, Bézier, linear and slow start. The rendered take is at the bottom, confirming that the slow end / start curves do render correctly.