s/has gained/has not gained/g

I'm pretty sure this was a typo

Author: pfalabella

src/libcore/iter.rs

@@ -2555,7 +2555,7 @@ impl<I: RandomAccessIterator, F> RandomAccessIterator for Inspect<I, F>
 #[unstable(feature = "iter_unfold")]
 #[derive(Clone)]
 #[deprecated(since = "1.2.0",
-             reason = "has gained enough traction to retain its position \
+             reason = "has not gained enough traction to retain its position \
                        in the standard library")]
 #[allow(deprecated)]
 pub struct Unfold<St, F> {
@@ -2567,7 +2567,7 @@ pub struct Unfold<St, F> {
 
 #[unstable(feature = "iter_unfold")]
 #[deprecated(since = "1.2.0",
-             reason = "has gained enough traction to retain its position \
+             reason = "has not gained enough traction to retain its position \
                        in the standard library")]
 #[allow(deprecated)]
 impl<A, St, F> Unfold<St, F> where F: FnMut(&mut St) -> Option<A> {
@@ -3018,7 +3018,7 @@ type IterateState<T, F> = (F, Option<T>, bool);
 /// from a given seed value.
 #[unstable(feature = "iter_iterate")]
 #[deprecated(since = "1.2.0",
-             reason = "has gained enough traction to retain its position \
+             reason = "has not gained enough traction to retain its position \
                        in the standard library")]
 #[allow(deprecated)]
 pub type Iterate<T, F> = Unfold<IterateState<T, F>, fn(&mut IterateState<T, F>) -> Option<T>>;
@@ -3027,7 +3027,7 @@ pub type Iterate<T, F> = Unfold<IterateState<T, F>, fn(&mut IterateState<T, F>)
 /// repeated applications of the given function `f`.
 #[unstable(feature = "iter_iterate")]
 #[deprecated(since = "1.2.0",
-             reason = "has gained enough traction to retain its position \
+             reason = "has not gained enough traction to retain its position \
                        in the standard library")]
 #[allow(deprecated)]
 pub fn iterate<T, F>(seed: T, f: F) -> Iterate<T, F> where