When trying to install the public templates on a site which has been upgraded from 5.1 I get this error:

 <snip>
EPiServerInstall Verbose: 0 : Copied Global.asax,
EPiServerInstall Verbose: 0 : Copied Global.asax.cs,
EPiServerInstall Verbose: 0 : Progress Status:   Activity:Installing  Description:Installing,
EPiServerInstall Verbose: 0 : Copied Install Public Templates.ps1,
EPiServerInstall Verbose: 0 : Copied PublicTemplates.csproj,
EPiServerInstall Verbose: 0 : Progress Status:   Activity:Installing  Description:Installing,
EPiServerInstall Verbose: 0 : Removed Install Public Templates.ps1,
EPiServerInstall Verbose: 0 : Progress Status:   Activity:Installing  Description:Installing,
EPiServerInstall Warning: 0 : Data Import: Exception: Language branch "sv               " is not defined[],
EPiServerInstall Warning: 0 : System.InvalidOperationException: The installation failed, and the rollback has been performed. ---> System.Configuration.Install.InstallException: Exception: Language branch "sv               " is not defined[]
   at EPiServer.Install.Modules.Installers.ImportDataInstaller.VerifyImportStatus(DataImporter importStatus)
   at EPiServer.Install.Modules.Installers.ImportDataInstaller.Install(IDictionary stateSaver)
   at System.Configuration.Install.Installer.Install(IDictionary stateSaver)
   at System.Configuration.Install.TransactedInstaller.Install(IDictionary savedState)
   --- End of inner exception stack trace ---
   at System.Configuration.Install.TransactedInstaller.Install(IDictionary savedState)
   at EPiServer.Install.InstallationManager.DoInstall(),
EPiServerInstall Error: 0 : Error, System.Management.Automation.CmdletInvocationException: Exception: Language branch "sv               " is not defined[] ---> System.Configuration.Install.InstallException: Exception: Language branch "sv               " is not defined[]
   at EPiServer.Install.InstallationManager.DoInstall()
   at EPiServer.Install.InstallationManager.CommitBulkInstall()
   at EPiServer.Install.Common.Cmdlets.CommitBulkInstallCmdlet.ProcessRecord()
   at System.Management.Automation.Cmdlet.DoProcessRecord()
   at System.Management.Automation.CommandProcessor.ProcessRecord()
   --- End of inner exception stack trace ---
   at System.Management.Automation.Internal.PipelineProcessor.SynchronousExecuteEnumerate(Object input, Hashtable errorResults, Boolean enumerate)
   at System.Management.Automation.Parser.PipelineNode.Execute(Array input, Pipe outputPipe, ArrayList& resultList)
   at System.Management.Automation.Parser.StatementListNode.Execute(Array input, Pipe outputPipe, ArrayList& resultList)

What gives?