After upgrading to 1.42 of the plugin, using the "Emulate clean checkout by first deleting unversioned/ignored files, then 'svn update'" svn strategy intermittently results in errors that look like the following:

ERROR: Failed to update svn://<path>
org.tmatesoft.svn.core.SVNException: svn: E155017: Checksum mismatch while updating '/opt/jenkins/jobs/<job>/workspace/<path to folder>/.svn/text-base/<filename>.svn-base'; expected: '151afc3b6d79443cc57fd52080d5f4d7', actual: '97acf6bf0db0d86168866633488b1a93'
at org.tmatesoft.svn.core.internal.wc.SVNErrorManager.error(SVNErrorManager.java:85)
at org.tmatesoft.svn.core.internal.wc.SVNErrorManager.error(SVNErrorManager.java:69)
at org.tmatesoft.svn.core.internal.io.svn.SVNEditModeReader.driveEditor(SVNEditModeReader.java:250)
at org.tmatesoft.svn.core.internal.io.svn.SVNRepositoryImpl.update(SVNRepositoryImpl.java:1503)
at org.tmatesoft.svn.core.internal.wc16.SVNUpdateClient16.update(SVNUpdateClient16.java:557)
at org.tmatesoft.svn.core.internal.wc16.SVNUpdateClient16.doUpdate(SVNUpdateClient16.java:414)
at org.tmatesoft.svn.core.internal.wc16.SVNUpdateClient16.doUpdate(SVNUpdateClient16.java:324)
at org.tmatesoft.svn.core.internal.wc2.old.SvnOldUpdate.run(SvnOldUpdate.java:27)
at org.tmatesoft.svn.core.internal.wc2.old.SvnOldUpdate.run(SvnOldUpdate.java:11)
at org.tmatesoft.svn.core.internal.wc2.SvnOperationRunner.run(SvnOperationRunner.java:20)
at org.tmatesoft.svn.core.wc2.SvnOperationFactory.run(SvnOperationFactory.java:1221)
at org.tmatesoft.svn.core.wc2.SvnOperation.run(SvnOperation.java:292)
at org.tmatesoft.svn.core.wc.SVNUpdateClient.doUpdate(SVNUpdateClient.java:315)
at org.tmatesoft.svn.core.wc.SVNUpdateClient.doUpdate(SVNUpdateClient.java:295)
at org.tmatesoft.svn.core.wc.SVNUpdateClient.doUpdate(SVNUpdateClient.java:391)
at hudson.scm.subversion.UpdateUpdater$TaskImpl.perform(UpdateUpdater.java:136)
at hudson.scm.subversion.WorkspaceUpdater$UpdateTask.delegateTo(WorkspaceUpdater.java:144)
at hudson.scm.SubversionSCM$CheckOutTask.perform(SubversionSCM.java:789)
at hudson.scm.SubversionSCM$CheckOutTask.invoke(SubversionSCM.java:770)
at hudson.scm.SubversionSCM$CheckOutTask.invoke(SubversionSCM.java:753)
at hudson.FilePath.act(FilePath.java:842)
at hudson.FilePath.act(FilePath.java:824)
at hudson.scm.SubversionSCM.checkout(SubversionSCM.java:743)
at hudson.scm.SubversionSCM.checkout(SubversionSCM.java:685)
at hudson.model.AbstractProject.checkout(AbstractProject.java:1242)
at hudson.model.AbstractBuild$AbstractBuildExecution.defaultCheckout(AbstractBuild.java:589)
at jenkins.scm.SCMCheckoutStrategy.checkout(SCMCheckoutStrategy.java:88)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:494)
at hudson.model.Run.execute(Run.java:1460)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:239)

I clicked the "Downgrade to 1.39" button in the installed plugins section, restarted Jenkins and the problem appears to be solved.

However, I notice the installed plugins section now says I have 1.34 installed, which is a little confusing.