I upgraded my successfully running Hudson from svn_tag version 1.4 to svn_tag
1.8, and then ran my simplest job (single repository, existing tree in
"last_successful" tag directory). It ran, but when it went to create the new
tag, it had this error:

moduleLocation: Remote ->http://svn/svn/trunk/apollo12/res
Failed to parse tag base URL 'http://svn/svn/tags/last-successful/res'. svn: URL
'http://svn/svn/tags/last-successful/res/..' contains .. element
Delete old tag http://svn/svn/tags/last-successful/res.
FATAL: null
java.lang.NullPointerException
at
org.tmatesoft.svn.core.wc.DefaultSVNRepositoryPool.createRepository(DefaultSVNRepositoryPool.java:210)
at
org.tmatesoft.svn.core.wc.SVNBasicClient.createRepository(SVNBasicClient.java:297)
at
org.tmatesoft.svn.core.wc.SVNBasicClient.createRepository(SVNBasicClient.java:289)
at org.tmatesoft.svn.core.wc.SVNCommitClient.doImport(SVNCommitClient.java:479)
at org.tmatesoft.svn.core.wc.SVNCommitClient.doImport(SVNCommitClient.java:464)
at org.tmatesoft.svn.core.wc.SVNCommitClient.doImport(SVNCommitClient.java:430)
at hudson.plugins.svn_tag.SvnTagPlugin.perform(SvnTagPlugin.java:209)
at hudson.plugins.svn_tag.SvnTagPublisher.perform(SvnTagPublisher.java:79)
at
hudson.model.AbstractBuild$AbstractRunner.performAllBuildStep(AbstractBuild.java:309)
at
hudson.model.AbstractBuild$AbstractRunner.performAllBuildStep(AbstractBuild.java:297)
at hudson.model.Build$RunnerImpl.cleanUp(Build.java:127)
at hudson.model.Run.run(Run.java:823)
at hudson.model.Build.run(Build.java:84)
at hudson.model.ResourceController.execute(ResourceController.java:70)
at hudson.model.Executor.run(Executor.java:88)

It did delete the existing directory under tags, but failed to create a new one.
I didn't do any reconfiguring of the job - I only updated the svn_tag plugin
version (so the "Tag Base URL" is unchanged at
"http://svn/svn/tags/last-successful/res")

Thanks for your efforts!