foldme; backtrack, don't repeat the limit const

Signed-off-by: Daniel Silverstone <[email protected]>

Author: kinnison

src/dist/dist.rs

@@ -622,8 +622,9 @@ fn update_from_dist_<'a>(
         // The limit of 21 days is an arbitrary selection, so we let the user override it.
         const BACKTRACK_LIMIT_DEFAULT: i32 = 21;
         let provided = env::var("RUSTUP_BACKTRACK_LIMIT")
-            .unwrap_or_else(|_| format!("{}", BACKTRACK_LIMIT_DEFAULT));
-        let provided = provided.parse().unwrap_or(BACKTRACK_LIMIT_DEFAULT);
+            .ok()
+            .and_then(|v| v.parse().ok())
+            .unwrap_or(BACKTRACK_LIMIT_DEFAULT);
         Some(if provided < 1 { 1 } else { provided })
     };