When Hudson's home directory does not exist, this is the exception thrown:

java.lang.Error: java.io.IOException: No such file or directory
at hudson.WebAppMain.contextInitialized(WebAppMain.java:88)
at
org.mortbay.jetty.handler.ContextHandler.startContext(ContextHandler.java:511)
at org.mortbay.jetty.servlet.Context.startContext(Context.java:135)
at
org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1191)
at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:481)
at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:434)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
at
org.mortbay.jetty.handler.HandlerCollection.doStart(HandlerCollection.java:147)
at
org.mortbay.jetty.handler.ContextHandlerCollection.doStart(ContextHandlerCollection.java:120)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
at
org.mortbay.jetty.handler.HandlerCollection.doStart(HandlerCollection.java:147)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:117)
at org.mortbay.jetty.Server.doStart(Server.java:210)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
at org.mortbay.xml.XmlConfiguration.main(XmlConfiguration.java:929)
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.mortbay.start.Main.invokeMain(Main.java:183)
at org.mortbay.start.Main.start(Main.java:497)
at org.mortbay.start.Main.main(Main.java:115)
Caused by: java.io.IOException: No such file or directory
at java.io.UnixFileSystem.createFileExclusively(Native Method)
at java.io.File.checkAndCreate(File.java:1345)
at java.io.File.createTempFile(File.java:1434)
at hudson.util.AtomicFileWriter.<init>(AtomicFileWriter.java:27)
at hudson.util.TextFile.write(TextFile.java:50)
at hudson.TcpSlaveAgentListener.<init>(TcpSlaveAgentListener.java:75)
at hudson.model.Hudson.<init>(Hudson.java:197)
at hudson.WebAppMain.contextInitialized(WebAppMain.java:86)
... 22 more

The attached patch fixes that problem by properly checking that the directory
exists, and reports a meaningful error.