Fix a bug where SIG API spots could be re-tagged as another SIG e.g. WAB if that was named in the comment.

spotproviders/wwff.py

@@ -28,6 +28,7 @@ class WWFF(HTTPSpotProvider):
                         freq=float(source_spot["frequency_khz"]) * 1000,
                         mode=source_spot["mode"].upper(),
                         comment=source_spot["remarks"],
+                        sig="WWFF",
                         sig_refs=[SIGRef(id=source_spot["reference"], sig="WWFF", name=source_spot["reference_name"])],
                         time=datetime.fromtimestamp(source_spot["spot_time"], tz=pytz.UTC).timestamp(),
                         dx_latitude=source_spot["latitude"],