Ignores -- as a key or empty value

[vlivyur]

Here in version 18 someone added literally "--=" as a key and value. But level0 loaded just this:

node 513394396: 51.2568140, 7.0880123
  crossing = traffic_signals
  highway = crossing

way 9222414
  destination = Velbert;Essen
  destination:ref = A 535
  highway = motorway_link
  lanes = 1
  maxspeed = none
  oneway = yes
  surface = asphalt
  nd 267281210
  nd 1223296664
  nd 513394396
  nd 267282842

node 267281210: 51.2566463, 7.0886820
node 267282842: 51.2568612, 7.0879034
node 1223296664: 51.2567463, 7.0881841

and no "-- = ". So it's impossible to delete it from the way. And if I try to upload this to OSM it says that there is nothing to upload.

I guess it's an issue with just this website, because it's possible to delete it with the plugin OpenStreetMap Tags Editor in FF