text: This is quite normal. The user didn't have the time to map the river, so he just started it. In this cases it's good to leave a fixme tag in the last node, asking other mappers to continue until completing the river.
  As an example, I continued the river like 30 km to the East, and left a fixme tag: https://www.openstreetmap.org/node/4710284183 (fixme="Completez SVP!")