Using 'split adjacent ways' on multipolygons is unpredictable.

[eladner]

What steps will reproduce the problem?

1. create a multi-segment multipolygon
2. draw a segment internally from a node on one way to a node on another way
3. Execute Split Adjacent Ways (ctl-alt-shift-P)

What is the expected result?

segments are split at the internal way and still members of the multipolygon.

What happens instead?

sometimes (not all the time) one portion of a segment split by the adjacent way is removed from the multipolygon.

Sometimes, it will remove an attribute off one of the ways.

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

URL:http://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2018-02-23 00:01:20 +0100 (Fri, 23 Feb 2018)
Build-Date:2018-02-22 23:03:41
Revision:13450
Relative:URL: ^/trunk

Identification: JOSM/1.5 (13450 en) Linux Ubuntu 16.04.3 LTS
Memory Usage: 1205 MB / 7282 MB (900 MB allocated, but free)
Java version: 1.8.0_161-b12, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: :0.0 1920x1080
Maximum Screen Size: 1920x1080
Dataset consistency test: No problems found

Plugins:
+ AddrInterpolation (34061)
+ CommandLine (33984)
+ Create_grid_of_ways (33856)
+ FastDraw (33731)
+ FixAddresses (33963)
+ OpeningHoursEditor (33876)
+ PicLayer (34021)
+ SimplifyArea (33918)
+ alignways (33784)
+ apache-commons (33668)
+ buildings_tools (34040)
+ dataimport (33581)
+ download_along (33710)
+ ejml (32680)
+ ext_tools (33889)
+ geotools (33958)
+ gpsblam (33776)
+ importvec (33902)
+ jts (32699)
+ log4j (32699)
+ merge-overlap (34056)
+ opendata (34072)
+ reltoolbox (33708)
+ reverter (34036)
+ splinex (33844)
+ turnrestrictions (33780)
+ utilsplugin2 (33991)
+ waydownloader (33910)

Tagging presets:
+ https://josm.openstreetmap.de/josmfile?page=Presets/OneClick&zip=1

Map paint styles:
- https://josm.openstreetmap.de/josmfile?page=Styles/LessObtrusiveNodes&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Fixme&style&zip=1

Last errors/warnings:
- W: Invalid jar file ''<josm.pref>/plugins/opendata.jar.new'' (exists: false, canRead: false)
- W: No configuration settings found.  Using hardcoded default values for all pools.

[eladner]

example showing some of the defects. MP highlighting is subtle because it was water. zoom in and it's more apparent.

[eladner]

reworked the example as an OSM file and easier to see.