Merging existing revert-changeset information to empty dataset fails

[Larry0ua]

What steps will reproduce the problem?

1. Install reverter plugin,
2. Restart JOSM
3. Do not download any data, call reverter action, specify a changeset ID
4. See an exception in JOSM core.

This looks like a problem with the reverter plugin, but if it is not - please reassign

Repository Root: http://josm.openstreetmap.de/svn
Build-Date: 2013-04-15 01:35:00
Last Changed Author: Don-vip
Revision: 5866
Repository UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
URL: http://josm.openstreetmap.de/svn/trunk
Last Changed Date: 2013-04-15 01:40:02 +0200 (Mon, 15 Apr 2013)
Last Changed Rev: 5866

Identification: JOSM/1.5 (5866 en) Windows 7 64-Bit
Memory Usage: 247 MB / 989 MB (175 MB allocated, but free)
Java version: 1.7.0_17, Oracle Corporation, Java HotSpot(TM) Client VM
Operating system: Windows 7 64-Bit
VM arguments: [-Djava.security.policy=file:C:\Program Files (x86)\Java\jre7\lib\security\javaws.policy, -DtrustProxy=true, -Xverify:remote, -Djnlpx.home=C:\Program Files (x86)\Java\jre7\bin, -Djnlpx.origFilenameArg=D:\josm.jnlp, -Djnlpx.remove=true, -Dsun.awt.warmup=true, -Xbootclasspath/a:C:\Program Files (x86)\Java\jre7\lib\javaws.jar;C:\Program Files (x86)\Java\jre7\lib\deploy.jar;C:\Program Files (x86)\Java\jre7\lib\plugin.jar, -Xmx1G, -Xms256M, -Djnlpx.splashport=55006, -Djnlpx.jvm=C:\Program Files (x86)\Java\jre7\bin\javaw.exe, -Djnlpx.vmargs=-Xmx1G -Xms256M]
Dataset consistency test: No problems found

Plugin: FastDraw (29457)
Plugin: ImageryCache (29484)
Plugin: OpeningHoursEditor (29435)
Plugin: PicLayer (29435)
Plugin: buildings_tools (29435)
Plugin: imagery_offset_db (29467)
Plugin: jts (29435)
Plugin: print (29435)
Plugin: public_transport (29435)
Plugin: reltoolbox (29459)
Plugin: reverter (29435)
Plugin: utilsplugin2 (29435)
Plugin: vectorizer (${version.entry.commit.revision})

java.lang.NullPointerException
	at org.openstreetmap.josm.gui.layer.OsmDataLayer.mergeFrom(OsmDataLayer.java:409)
	at org.openstreetmap.josm.gui.layer.OsmDataLayer.mergeFrom(OsmDataLayer.java:355)
	at reverter.ChangesetReverter.downloadMissingPrimitives(ChangesetReverter.java:242)
	at reverter.RevertChangesetTask.realRun(RevertChangesetTask.java:80)
	at org.openstreetmap.josm.gui.PleaseWaitRunnable.doRealRun(PleaseWaitRunnable.java:82)
	at org.openstreetmap.josm.gui.PleaseWaitRunnable.run(PleaseWaitRunnable.java:145)
	at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
	at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
	at java.util.concurrent.FutureTask.run(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)

[Larry0ua]

I used 15675308 changeset for reverting, it could be useful for locating a bug as it contains only one relation for undeleting, no ways and points.

[Don-vip]

Strange, I can only reproduce with this changeset.

[Don-vip]

In 5869/josm:

fix #8609 - NPE