the following error:

ERROR: Failed to clean the workspace
java.io.IOException: Unable to delete C:\home\duns\riscure\hg\riscure-hudson\jobs\riscure-
inspector-drivers-3.0.x\workspace\.hg\hgrc
at hudson.Util.deleteFile(Util.java:195)
at hudson.Util.deleteRecursive(Util.java:226)
at hudson.Util.deleteContentsRecursive(Util.java:161)
at hudson.Util.deleteRecursive(Util.java:225)
at hudson.Util.deleteContentsRecursive(Util.java:161)
at hudson.Util.deleteRecursive(Util.java:225)
at hudson.FilePath$6.invoke(FilePath.java:460)
at hudson.FilePath$6.invoke(FilePath.java:458)
at hudson.FilePath.act(FilePath.java:388)
at hudson.FilePath.deleteRecursive(FilePath.java:458)
at hudson.plugins.mercurial.MercurialSCM.clone(MercurialSCM.java:317)
at hudson.plugins.mercurial.MercurialSCM.checkout(MercurialSCM.java:211)
at hudson.model.AbstractProject.checkout(AbstractProject.java:664)
at hudson.model.AbstractBuild$AbstractRunner.checkout(AbstractBuild.java:260)
at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:234)
at hudson.model.Run.run(Run.java:793)
at hudson.maven.MavenModuleSetBuild.run(MavenModuleSetBuild.java:205)
at hudson.model.ResourceController.execute(ResourceController.java:70)
at hudson.model.Executor.run(Executor.java:88)
finished: FAILURE

happens because the .hg/hgrc file is not closed, while Hudson is checking if the workspace
can be updated or needs a clone. It happens on "branches" since these (probably) need to be
re-checked out.

Add a r.close() statement to the HrRc.java file, ctor: HgRc(Reader input, File hgrc)
and things start to work.