Using /tp only with rotation should not dismount the player

The tp should not update the player's position by using for example: "/tp @p ~ ~ ~ 1 1" but only update the rotation. Since this causes the entity to dismount the rided entity.

One possible fix would be adding an other parameter that just accepts rotation:
/tp <selector> rotation <rotation>

Or adding a new command: /rotation <selector> <x> <y>