The new ignore-existing make this recipe useless in some cases

[keul]

In older versions of the recipe we where able to overwrite existing files with new ones downloaded by the recipe itself.

Newer version now fail if one or more files are will be overwritten by the recipe.
The new versions introduced this ignore-existing option, but in the case above this is still useless as we can only

• let buildout fail
• ignore existings files

In facts we are no more able to overwrite files.