Perhaps hudson is getting confused as to when it's a local copy vs. remote copy.
Maybe this code FilePath.copyRecursiveTo:

if(this.channel==target.channel)

{ // local to local copy. ... }

else
if(this.channel==null)

{ // local -> remote copy ... }

else {
// remote -> local copy
}

should be using some sort of .equals() instead of memory pointer compare??

http://www.nabble.com/Archiving-Site%3A-IOException%3A-Not-in-GZIP-format-to20325401.html

http://www.nabble.com/java.io.IOException%3A-Not-in-GZIP-format-at-hudson.FilePath.readFromTar(FilePath.java%3A996)-to20173327.html

http://www.nabble.com/Job-Randomly-Failing-due-to-hudson.util.IOException2%3A-java.io.IOException%3A-Not-in-GZIP-format-to19152197.html

stacktrace in hudson console:

[INFO] [site:site]
[WARNING] No URL defined for the project - decoration links will not be resolved
[INFO] Generating "Plugin Management" report.
[INFO] Generating "Mailing Lists" report.
[INFO] Generating "Continuous Integration" report.
[INFO] Generating "Dependency Management" report.
[INFO] Generating "Project License" report.
[INFO] Generating "Project Team" report.
[INFO] Generating "Source Repository" report.
[INFO] Generating "About" report.
[INFO] Generating "Issue Tracking" report.
[INFO] Generating "Project Summary" report.
[INFO] Generating "Project Plugins" report.
[INFO] Generating "Dependency Convergence" report.
[INFO] Generating "Dependencies" report.
[FINDBUGS] File encoding has not been set in pom.xml, using platform encoding
UTF-8, i.e. build is platform dependent (see <a
href="http://docs.codehaus.org/display/MAVENUSER/POM+Element+for+Source+File+Encoding">Maven
FAQ</a>).
[FINDBUGS] A total of 0 annotations have been found for priority HIGH
[FINDBUGS] A total of 0 annotations have been found for priority NORMAL
[FINDBUGS] A total of 0 annotations have been found for priority LOW
[CHECKSTYLE] File encoding has not been set in pom.xml, using platform encoding
UTF-8, i.e. build is platform dependent (see <a
href="http://docs.codehaus.org/display/MAVENUSER/POM+Element+for+Source+File+Encoding">Maven
FAQ</a>).
[CHECKSTYLE] A total of 0 annotations have been found for priority HIGH
[CHECKSTYLE] A total of 0 annotations have been found for priority NORMAL
[CHECKSTYLE] A total of 0 annotations have been found for priority LOW
[PMD] File encoding has not been set in pom.xml, using platform encoding UTF-8,
i.e. build is platform dependent (see <a
href="http://docs.codehaus.org/display/MAVENUSER/POM+Element+for+Source+File+Encoding">Maven
FAQ</a>).
[PMD] A total of 0 annotations have been found for priority HIGH
[PMD] A total of 0 annotations have been found for priority NORMAL
[PMD] A total of 0 annotations have been found for priority LOW
[TASKS] Scipping maven reporter: there is already a result available.
[HUDSON] Archiving site
FATAL: Unable to copy site from

{0}

to

{1}

hudson.util.IOException2: hudson.util.IOException2: Not in GZIP format
stream=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
at hudson.FilePath.copyRecursiveTo(FilePath.java:919)
at hudson.FilePath.copyRecursiveTo(FilePath.java:847)
at hudson.maven.reporters.MavenSiteArchiver.postExecute(MavenSiteArchiver.java:52)
at
hudson.maven.MavenModuleSetBuild$Builder.postExecute(MavenModuleSetBuild.java:603)
at hudson.maven.MavenBuilder$Adapter.postExecute(MavenBuilder.java:267)
at
hudson.maven.agent.PluginManagerInterceptor$1MojoIntercepterImpl.callPost(PluginManagerInterceptor.java:147)
at
hudson.maven.agent.PluginManagerInterceptor.executeMojo(PluginManagerInterceptor.java:160)
at
org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:558)
at
org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:499)
at
org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:478)
at
org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:330)
at
org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:291)
at
org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:142)
at
org.apache.maven.lifecycle.LifecycleExecutorInterceptor.execute(LifecycleExecutorInterceptor.java:42)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:336)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:129)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:287)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
at hudson.maven.agent.Main.launch(Main.java:135)
at hudson.maven.MavenBuilder.call(MavenBuilder.java:139)
at hudson.maven.MavenModuleSetBuild$Builder.call(MavenModuleSetBuild.java:542)
at hudson.maven.MavenModuleSetBuild$Builder.call(MavenModuleSetBuild.java:488)
at hudson.remoting.UserRequest.perform(UserRequest.java:69)
at hudson.remoting.UserRequest.perform(UserRequest.java:23)
at hudson.remoting.Request$2.run(Request.java:213)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:417)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:269)
at java.util.concurrent.FutureTask.run(FutureTask.java:123)
at
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:650)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:675)
at java.lang.Thread.run(Thread.java:595)
Caused by: java.util.concurrent.ExecutionException: hudson.util.IOException2:
Not in GZIP format
stream=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
at hudson.remoting.Channel$1.adapt(Channel.java:486)
at hudson.remoting.Channel$1.adapt(Channel.java:481)
at hudson.remoting.FutureAdapter.get(FutureAdapter.java:32)
at hudson.FilePath.copyRecursiveTo(FilePath.java:917)
... 35 more
Caused by: hudson.util.IOException2: Not in GZIP format
stream=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
at hudson.FilePath.readFromTar(FilePath.java:1018)
at hudson.FilePath.access$300(FilePath.java:121)
at hudson.FilePath$24.invoke(FilePath.java:908)
at hudson.FilePath$24.invoke(FilePath.java:905)
at hudson.FilePath$FileCallableWrapper.call(FilePath.java:1229)
... 9 more
Caused by: java.io.IOException: Not in GZIP format
at java.util.zip.GZIPInputStream.readHeader(GZIPInputStream.java:132)
at java.util.zip.GZIPInputStream.<init>(GZIPInputStream.java:58)
at java.util.zip.GZIPInputStream.<init>(GZIPInputStream.java:68)
at hudson.FilePath.readFromTar(FilePath.java:1014)
... 13 more
[HUDSON] Archiving
/opt/hudson/data/jobs/CtmsWebApps-nightly/workspace/trunk/CtmsLabtrakEjb/dependency-reduced-pom.xml
to
/opt/hudson/data/jobs/CtmsWebApps-nightly/modules/org.calgb.ctms$CtmsLabtrakEjb/builds/2009-02-24_04-20-12/archive/org.calgb.ctms/CtmsLabtrakEjb/4.6-SNAPSHOT/dependency-reduced-pom.xml
[HUDSON] Archiving
/opt/hudson/data/jobs/CtmsWebApps-nightly/workspace/trunk/CtmsLabtrakEjb/target/CtmsLabtrakEjb-4.6-SNAPSHOT.jar
to
/opt/hudson/data/jobs/CtmsWebApps-nightly/modules/org.calgb.ctms$CtmsLabtrakEjb/builds/2009-02-24_04-20-12/archive/org.calgb.ctms/CtmsLabtrakEjb/4.6-SNAPSHOT/CtmsLabtrakEjb-4.6-SNAPSHOT.jar
[INFO] ------------------------------------------------------------------------
[INFO] Building CtmsLabtrakWeb
[INFO] task-segment: [clean, install, site]
[INFO] ------------------------------------------------------------------------