Don't initialize ignores for file arguments.

We'll never use them, so it's wasted effort.

src/args.rs

@@ -673,6 +673,10 @@ impl Args {
     pub fn walker(&self, path: &Path) -> Result<walk::Iter> {
         let wd = WalkDir::new(path).follow_links(self.follow);
         let mut ig = Ignore::new();
+        // Only register ignore rules if this is a directory. If it's a file,
+        // then it was explicitly given by the end user, so we always search
+        // it.
+        if path.is_dir() {
             ig.ignore_hidden(!self.hidden);
             ig.no_ignore(self.no_ignore);
             ig.no_ignore_vcs(self.no_ignore_vcs);
@@ -683,6 +687,7 @@ impl Args {
             if let Some(ref overrides) = self.glob_overrides {
                 ig.add_override(overrides.clone());
             }
+        }
         Ok(walk::Iter::new(ig, wd))
     }
 }