Respond to feedback in https://codereview.chromium.org/1902993003/.

lib/src/utils.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// Generic utility functions. Stuff that should possibly be in core.
 import 'dart:async';
 import "dart:convert";
 import 'dart:io';
 import 'dart:math' as math;
 
-import "package:convert/convert.dart";
 import "package:crypto/crypto.dart" as crypto;
 import 'package:path/path.dart' as path;
 import "package:stack_trace/stack_trace.dart";
 
 import 'exceptions.dart';
 import 'io.dart';
 import 'log.dart' as log;
 
 export 'asset/dart/utils.dart';
 
@@ skipping 459 matching lines @@
 /// Returns whether or not [str] ends with [matcher].
 bool endsWithPattern(String str, Pattern matcher) {
   for (var match in matcher.allMatches(str)) {
     if (match.end == str.length) return true;
   }
   return false;
 }
 
 /// Returns the hex-encoded sha1 hash of [source].
 String sha1(String source) =>
-    hex.encode(crypto.sha1.convert(source.codeUnits).bytes);
+    crypto.sha1.convert(UTF8.encode(source)).toString();
 
 /// Returns the base64-encoded sha1 hash of [stream].
 Future<String> sha1Stream(Stream<List<int>> stream) async {
   crypto.Digest digest;
 
   var digestSink = new ChunkedConversionSink<crypto.Digest>.withCallback(
       (digests) {
     digest = digests.single;
   });
 
@@ skipping 470 matching lines @@
   } else {
     throw new ApplicationException(message);
   }
 }
 
 /// Throw a [DataException] with [message] to indicate that the command has
 /// failed because of invalid input data.
 ///
 /// This will report the error and cause pub to exit with [exit_codes.DATA].
 void dataError(String message) => throw new DataException(message);