Hemiptera Bugtracker at bugs.linux-forks.de
From: OP The current coupling algorithm bugs around when trying to couple wagons
with a very short wagon_span.
This can be tested using the minecarts from rubberduck's moretrains.
From: OP Should be solved by 1f3a4c3b and 4989da36. Should be thoroughly tested though, there still seems to be weird behavior in rare cases. I suspect it has something to do with a potentially longer partner train still exercising the buggy coupling.