after the upgrade to the latest Hudson (1.377) and Rake plugin (1.7) all jobs that are using the Rake plugin with "Rake Version" set to "(Default)" have started failing with:

Started by user xxxx
Building remotely on ci-slave-01
[Core-developing-deploy] $ ruby -v D:\DOCUME~1_service\LOCALS~1\Temp\hudson3144810132813567851.rb
ruby 1.8.7 (2010-08-16 patchlevel 302) [i386-mingw32]
Copied 16 artifacts from Core-developing-package #117
FATAL: null
java.lang.NullPointerException
at hudson.plugins.rake.Rake.perform(Rake.java:122)
at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:19)
at hudson.model.AbstractBuild$AbstractRunner.perform(AbstractBuild.java:601)
at hudson.model.Build$RunnerImpl.build(Build.java:174)
at hudson.model.Build$RunnerImpl.doRun(Build.java:138)
at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:416)
at hudson.model.Run.run(Run.java:1273)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:137)

Selecting a specific version of Rake fixes this issue in some cases, but in cases where the path to Ruby is different on different boxes (slaves) it may still fail.

Prior to this update, we were using the Default rake installation in most cases, so as long as it was available in the PATH on the slave, it worked.