Fix clippy

Author: Mark-Simulacrum

src/prelude.rs

@@ -9,6 +9,7 @@ pub trait FailExt {
 }
 
 impl FailExt for dyn Fail {
+    #[allow(clippy::manual_map)]
     fn downcast_ctx<T: Fail>(&self) -> Option<&T> {
         if let Some(res) = self.downcast_ref::<T>() {
             Some(res)

src/runner/unstable_features.rs

@@ -77,6 +77,7 @@ fn eat_token<'a>(s: Option<&'a str>, tok: &str) -> Option<&'a str> {
 
 fn eat_whitespace(s: Option<&str>) -> Option<&str> {
     s.and_then(|s| {
+        #[allow(clippy::manual_map)]
         if let Some(i) = s.find(|c: char| !c.is_whitespace()) {
             Some(&s[i..])
         } else {