Use the bytecount crate for fast line counting.

Fixes #128

tests/tests.rs

@@ -789,6 +789,15 @@ clean!(regression_127, "Sherlock", ".", |wd: WorkDir, mut cmd: Command| {
     assert_eq!(lines, expected);
 });
 
+// See: https://github.com/BurntSushi/ripgrep/issues/128
+clean!(regression_128, "x", ".", |wd: WorkDir, mut cmd: Command| {
+    wd.create_bytes("foo", b"01234567\x0b\n\x0b\n\x0b\n\x0b\nx");
+    cmd.arg("-n");
+
+    let lines: String = wd.stdout(&mut cmd);
+    assert_eq!(lines, "foo:5:x\n");
+});
+
 // See: https://github.com/BurntSushi/ripgrep/issues/131
 //
 // TODO(burntsushi): Darwin doesn't like this test for some reason.

tests/workdir.rs

@@ -43,9 +43,14 @@ impl WorkDir {
 
     /// Create a new file with the given name and contents in this directory.
     pub fn create<P: AsRef<Path>>(&self, name: P, contents: &str) {
+        self.create_bytes(name, contents.as_bytes());
+    }
+
+    /// Create a new file with the given name and contents in this directory.
+    pub fn create_bytes<P: AsRef<Path>>(&self, name: P, contents: &[u8]) {
         let path = self.dir.join(name);
         let mut file = nice_err(&path, File::create(&path));
-        nice_err(&path, file.write_all(contents.as_bytes()));
+        nice_err(&path, file.write_all(contents));
         nice_err(&path, file.flush());
     }