Hello again! (I've been going through your changesets for which you requested review.) In this one, that "extra line" you removed was part of the administrative boundary [1] for Tanasbourne. Even if a feature has no tags, it might be part of a multipolygon or other relation. [2]
Fortunately, in this case it was easy to restore, which I just took care of. Arguably you were following the OSM good practice of "be bold". :)

Let me know if you have any questions about that, and thanks for your contributions!!

[1] More info on admin boundaries: https://wiki.openstreetmap.org/wiki/Tag%3aboundary=administrative

[2] More info on multipolygons: https://wiki.openstreetmap.org/wiki/Relation:multipolygon