4.03 or higher, this feature is / will be
implemented as option
segmentation at break=false.
First, the behaviour is not a bug. If a break occurs at the segmentation between upper and lower part, then the segmentation line and the lower part go to the next page. There, the segmentation is displayed to signal that the lower part starts.
bicolor, the color change also signals the begin of the lower part. So, it may be preferable to have no explicit segmentation line here. I take it as a feature request that the segmentation is optionally not drawn on page breaks :-)
For 'faked' segmentations with
\tcbline, there already is the option to use
\tcbline* instead to get this feature.
For 'real' segmentations, this option is currently not available. But, I think we can do it with the following new option:
With it, the segmentation line is not drawn at the begin of the splitted box. I have to investigate, if this causes some unwanted side-effects. Also, a good name for the feature has to be found (suggestions are welcome).
The full example code is: