plugin adds duplicated member to associatedStreet relation

[GerdP]

What steps will reproduce the problem?

1. Load attached file
2. Select building
3. Presst Shift+T for terracer plugin
4. Enter 2 as lowest number, 4 as highest number, make sure that checkbox for "add to existing associatedStreet relation" is enabled
5. Press OK

What is the expected result?

Relation should have 3 members, the street and two with role house

What happens instead?

Relation has 4 members, the one with addr:housenumber=2 is duplicated

Please provide any additional information below. Attach a screenshot if possible.

URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2020-09-06 16:54:59 +0200 (Sun, 06 Sep 2020)
Build-Date:2020-09-07 01:30:48
Revision:17013
Relative:URL: ^/trunk

Identification: JOSM/1.5 (17013 en) Windows 10 64-Bit
OS Build number: Windows 10 Home 2004 (19041)
Memory Usage: 1120 MB / 3641 MB (628 MB allocated, but free)
Java version: 1.8.0_221-b11, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Look and Feel: com.sun.java.swing.plaf.windows.WindowsLookAndFeel
Screen: \Display0 1920x1080 (scaling 1.0x1.0)
Maximum Screen Size: 1920x1080
Best cursor sizes: 16x16 -> 32x32, 32x32 -> 32x32
VM arguments: [-XX:StartFlightRecording=name=MyRecording2,settings=d:\dbg\gerd.jfc, -XX:FlightRecorderOptions=defaultrecording=true,dumponexit=true,dumponexitpath=e:\ld\perf_20200928_101014.jfr]
Dataset consistency test: No problems found

Plugins:
+ OpeningHoursEditor (35414)
+ PolygonCutOut (v0.7)
+ apache-commons (35524)
+ buildings_tools (35500)
+ continuosDownload (91)
+ ejml (35313)
+ geotools (35169)
+ jaxb (35092)
+ jts (35122)
+ merge-overlap (35248)
+ o5m (35248)
+ opendata (35513)
+ pbf (35446)
+ poly (35248)
+ reverter (35556)
+ terracer (35499)
+ undelete (35521)
+ utilsplugin2 (35487)

[GerdP]

In 35558/osm:

fix #19853: plugin adds duplicated member to associatedStreet relation