Certain combinations of control point and path node give this bug: https://bugs.kde.org/show_bug.cgi?id=328537 They are most common with the begin and ending lines from the path tool, which is unnecessary. (It is a matter of making the controlpoint point the right way), so maybe we should add a check that the path tool doesn't make these odd looking nodes by default.
It is easier to fix an original bug in Qt than to find a working workaround in Krita :)