Fix (de)serialization of new types where the internal type is skipped

serde_derive/src/de.rs

@@ -1689,6 +1689,24 @@ fn deserialize_externally_tagged_variant(
             }
         }
         Style::Newtype => {
+            if variant.fields[0].attrs.skip_deserializing() {
+                let this = &params.this;
+                let let_default = match variant.fields[0].attrs.default() {
+                    attr::Default::Default => quote!(
+                        _serde::export::Default::default()
+                    ),
+                    attr::Default::Path(ref path) => quote!(
+                        #path()
+                    ),
+                    _ => unimplemented!(),
+                };
+
+
+                return quote_block! {
+                    try!(_serde::de::VariantAccess::unit_variant(__variant));
+                    _serde::export::Ok(#this::#variant_ident(#let_default))
+                };   
+            }
             deserialize_externally_tagged_newtype_variant(variant_ident, params, &variant.fields[0])
         }
         Style::Tuple => {