How to reproduce :

• in a model, insert a CVS folder in the folder of variants
• in the BO, generate a new skin with this model
  > it provoques an error :

  Caused by: org.apache.cocoon.ProcessingException: The generation of skin failed
  	at <map:mount> - resource://org/ametys/runtime/kernel/sitemap.xmap:144:82
  	at org.ametys.skinfactory.skins.GenerateSkinAction.act(GenerateSkinAction.java:113)
  	at org.apache.cocoon.components.treeprocessor.sitemap.ActTypeNode.invoke(ActTypeNode.java:125)
  	at org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:47)
  	at org.apache.cocoon.components.treeprocessor.sitemap.MatchNode.invoke(MatchNode.java:108)
  	at org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:69)
  	at org.apache.cocoon.components.treeprocessor.sitemap.PipelineNode.invoke(PipelineNode.java:143)
  	at org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:69)
  	at org.apache.cocoon.components.treeprocessor.sitemap.PipelinesNode.invoke(PipelinesNode.java:93)
  	at org.apache.cocoon.components.treeprocessor.ConcreteTreeProcessor.process(ConcreteTreeProcessor.java:236)
  	at org.apache.cocoon.components.treeprocessor.ConcreteTreeProcessor.buildPipeline(ConcreteTreeProcessor.java:194)
  	at org.apache.cocoon.components.treeprocessor.TreeProcessor.buildPipeline(TreeProcessor.java:267)
  	at org.apache.cocoon.components.treeprocessor.sitemap.MountNode.invoke(MountNode.java:111)
  	at org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:47)
  	at org.apache.cocoon.components.treeprocessor.sitemap.MatchNode.invoke(MatchNode.java:108)
  	at org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:69)
  	at org.apache.cocoon.components.treeprocessor.sitemap.PipelineNode.invoke(PipelineNode.java:143)
  	at org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:69)
  	at org.apache.cocoon.components.treeprocessor.sitemap.PipelinesNode.invoke(PipelinesNode.java:93)
  	at org.apache.cocoon.components.treeprocessor.ConcreteTreeProcessor.process(ConcreteTreeProcessor.java:236)
  	at org.apache.cocoon.components.treeprocessor.ConcreteTreeProcessor.buildPipeline(ConcreteTreeProcessor.java:194)
  	at org.apache.cocoon.components.treeprocessor.TreeProcessor.buildPipeline(TreeProcessor.java:267)
  	at org.apache.cocoon.components.source.impl.SitemapSource.init(SitemapSource.java:333)
  	... 62 more
  Caused by: java.lang.NullPointerException
  	at java.io.File.<init>(Unknown Source)
  	at org.ametys.skinfactory.parameters.VariantParameter.apply(VariantParameter.java:126)
  	at org.ametys.skinfactory.SkinFactoryComponent.applyParameter(SkinFactoryComponent.java:1064)
  	at org.ametys.skinfactory.SkinFactoryComponent.applyModelParameters(SkinFactoryComponent.java:987)
  	at org.ametys.skinfactory.SkinFactoryComponent.applyModelParameters(SkinFactoryComponent.java:934)
  	at org.ametys.skinfactory.skins.GenerateSkinAction.act(GenerateSkinAction.java:102)
  	... 83 more