I am running the jobConfigHistory plugin with mvn hpi:run from within IntelliJ IDEA 9.
I cannot create a new job or modify an existing job; I get a 500 error every time.
To reproduce:
1) Run with mvn hpi:run
2) go to http://localhost:8080/view/All/newJob
3) enter a unique job name
4) click "Build a free-style software project"
5) click OK

My browser then goes to http://localhost:8080/view/All/createItem
and contains this stack trace (there's more bug report after the stack trace):

HTTP ERROR: 500

Operation Changed on noon36 did not succeed

RequestURI=/view/All/createItem
Caused by:

java.lang.RuntimeException: Operation Changed on noon36 did not succeed
at hudson.plugins.jobConfigHistory.ConfigHistoryListenerHelper.createNewHistoryEntry(ConfigHistoryListenerHelper.java:123)
at hudson.plugins.jobConfigHistory.JobConfigHistorySaveableListener.onChange(JobConfigHistorySaveableListener.java:27)
at hudson.model.listeners.SaveableListener.fireOnChange(SaveableListener.java:80)
at hudson.model.AbstractItem.save(AbstractItem.java:220)
at hudson.model.Hudson.createProject(Hudson.java:1975)
at hudson.model.Hudson.createProject(Hudson.java:1952)
at hudson.model.Hudson.doCreateItem(Hudson.java:2518)
at hudson.model.AllView.doCreateItem(AllView.java:73)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.kohsuke.stapler.Function$InstanceFunction.invoke(Function.java:185)
at org.kohsuke.stapler.Function.bindAndInvoke(Function.java:101)
at org.kohsuke.stapler.Function.bindAndInvokeAndServeResponse(Function.java:54)
at org.kohsuke.stapler.MetaClass$1.doDispatch(MetaClass.java:74)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:30)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:492)
at org.kohsuke.stapler.MetaClass$6.doDispatch(MetaClass.java:180)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:30)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:492)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:408)
at org.kohsuke.stapler.Stapler.service(Stapler.java:117)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:491)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1074)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:94)
at hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:86)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1065)
at hudson.security.csrf.CrumbFilter.doFilter(CrumbFilter.java:47)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1065)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:84)
at hudson.security.ChainedServletFilter.doFilter(ChainedServletFilter.java:76)
at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:164)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1065)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:365)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:185)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:689)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:391)
at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:146)
at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139)
at org.mortbay.jetty.Server.handle(Server.java:285)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:457)
at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:765)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:628)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:209)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:357)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:329)
at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:475)
Caused by: java.io.IOException: Failed to detect encoding of /Users/bshine/src/os-hudson/plugins/jobConfigHistory/./work/jobs/noon36/config.xml
at hudson.XmlFile.sniffEncoding(XmlFile.java:272)
at hudson.XmlFile.readRaw(XmlFile.java:197)
at hudson.XmlFile.writeRawTo(XmlFile.java:214)
at hudson.XmlFile.asString(XmlFile.java:205)
at hudson.plugins.jobConfigHistory.ConfigHistoryListenerHelper.createNewHistoryEntry(ConfigHistoryListenerHelper.java:103)
... 50 more

Caused by:

java.io.IOException: Failed to detect encoding of /Users/bshine/src/os-hudson/plugins/jobConfigHistory/./work/jobs/noon36/config.xml
at hudson.XmlFile.sniffEncoding(XmlFile.java:272)
at hudson.XmlFile.readRaw(XmlFile.java:197)
at hudson.XmlFile.writeRawTo(XmlFile.java:214)
at hudson.XmlFile.asString(XmlFile.java:205)
at hudson.plugins.jobConfigHistory.ConfigHistoryListenerHelper.createNewHistoryEntry(ConfigHistoryListenerHelper.java:103)
at hudson.plugins.jobConfigHistory.JobConfigHistorySaveableListener.onChange(JobConfigHistorySaveableListener.java:27)
at hudson.model.listeners.SaveableListener.fireOnChange(SaveableListener.java:80)
at hudson.model.AbstractItem.save(AbstractItem.java:220)
at hudson.model.Hudson.createProject(Hudson.java:1975)
at hudson.model.Hudson.createProject(Hudson.java:1952)
at hudson.model.Hudson.doCreateItem(Hudson.java:2518)
at hudson.model.AllView.doCreateItem(AllView.java:73)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.kohsuke.stapler.Function$InstanceFunction.invoke(Function.java:185)
at org.kohsuke.stapler.Function.bindAndInvoke(Function.java:101)
at org.kohsuke.stapler.Function.bindAndInvokeAndServeResponse(Function.java:54)
at org.kohsuke.stapler.MetaClass$1.doDispatch(MetaClass.java:74)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:30)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:492)
at org.kohsuke.stapler.MetaClass$6.doDispatch(MetaClass.java:180)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:30)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:492)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:408)
at org.kohsuke.stapler.Stapler.service(Stapler.java:117)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:491)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1074)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:94)
at hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:86)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1065)
at hudson.security.csrf.CrumbFilter.doFilter(CrumbFilter.java:47)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1065)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:84)
at hudson.security.ChainedServletFilter.doFilter(ChainedServletFilter.java:76)
at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:164)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1065)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:365)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:185)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:689)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:391)
at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:146)
at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139)
at org.mortbay.jetty.Server.handle(Server.java:285)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:457)
at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:765)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:628)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:209)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:357)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:329)
at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:475)

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After doing this, while the browser is still on the 500 page, I examine the file on disk:
~/src/os-hudson/hudson/main $ ls -l /Users/bshine/src/os-hudson/plugins/jobConfigHistory/./work/jobs/noon36/config.xml
rw-rr- 1 bshine users 406 Feb 3 12:36 /Users/bshine/src/os-hudson/plugins/jobConfigHistory/./work/jobs/noon36/config.xml

Actually looking at the contents of the file, it looks reasonable:
ore /Users/bshine/src/os-hudson/plugins/jobConfigHistory/./work/jobs/noon36/config.xml
<?xml version='1.0' encoding='UTF-8'?>
<project>
<keepDependencies>false</keepDependencies>
<properties/>
<scm class="hudson.scm.NullSCM"/>
<canRoam>false</canRoam>
<disabled>false</disabled>
<blockBuildWhenUpstreamBuilding>false</blockBuildWhenUpstreamBuilding>
<triggers class="vector"/>
<concurrentBuild>false</concurrentBuild>
<builders/>
<publishers/>
<buildWrappers/>
</project>

Returning to http://localhost:8080/ the job I just created ("noon36") does not exist in the list of jobs.