never print the warning on CI

src/bootstrap/src/core/build_steps/format.rs

@@ -114,7 +114,7 @@ fn print_paths(verb: &str, adjective: Option<&str>, paths: &[String]) {
     } else {
         println!("fmt: {verb} {len} {adjective}files");
     }
-    if len > 1000 {
+    if len > 1000 && !CiEnv::is_ci() {
         println!("hint: if this number seems too high, try running `git fetch origin master");
     }
 }