Use mem::take instead of mem::replace with default

src/libcore/option.rs

@@ -845,7 +845,7 @@ impl<T> Option<T> {
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn take(&mut self) -> Option<T> {
-        mem::replace(self, None)
+        mem::take(self)
     }
 
     /// Replaces the actual value in the option by the value given in parameter,

src/libproc_macro/bridge/buffer.rs

@@ -78,7 +78,7 @@ impl<T: Copy> Buffer<T> {
     }
 
     pub(super) fn take(&mut self) -> Self {
-        mem::replace(self, Self::default())
+        mem::take(self)
     }
 
     pub(super) fn extend_from_slice(&mut self, xs: &[T]) {