chore: fix some comments

Signed-off-by: todaymoon <csgcgl@foxmail.com>

clippy_lints/src/operators/identity_op.rs

@@ -103,7 +103,7 @@ enum Parens {
 ///
 /// e.g. `-(x + y + 0)` cannot be reduced to `-x + y`, as the behavior changes silently.
 /// e.g. `1u64 + ((x + y + 0i32) as u64)` cannot be reduced to `1u64 + x + y as u64`, since
-/// the the cast expression will not apply to the same expression.
+/// the cast expression will not apply to the same expression.
 /// e.g. `0 + if b { 1 } else { 2 } + if b { 3 } else { 4 }` cannot be reduced
 /// to `if b { 1 } else { 2 } + if b { 3 } else { 4 }` where the `if` could be
 /// interpreted as a statement. The same behavior happens for `match`, `loop`,

rustc_tools_util/src/lib.rs

@@ -121,7 +121,7 @@ fn get_output(cmd: &str, args: &[&str]) -> Option<String> {
 pub fn rerun_if_git_changes() -> Option<()> {
     // Make sure we get rerun when the git commit changes.
     // We want to watch two files: HEAD, which tracks which branch we are on,
-    // and the file for that branch that tracks which commit is is on.
+    // and the file for that branch that tracks which commit is checked out.
 
     // First, find the `HEAD` file. This should work even with worktrees.
     let git_head_file = PathBuf::from(get_output("git", &["rev-parse", "--git-path", "HEAD"])?);