kevmo314 opened the ticket and wrote:

Running r10048

1. Build an electrified train depot.
2. Build an MP-54 electric train.
3. Add 7 passenger cars to that train.
4. Attempting to drag another car will give you the message:
   "Multiple units cannot be longer than 8."
5. Clone the train.
6. Control-drag the entire second train onto the first train.
7. Attempt to clone the new train with 16 units.

In the attached savegame, just attempt to clone the train in the depot.

Either allowing the trains longer than 8 to be cloned, or fixing the cap will work fine as a fix.

Reported version: trunk
Operating system: Windows

This issue was imported from FlySpray: https://bugs.openttd.org/task/845