Explicitly configure git committer.

utils/pub/io.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.
 
 /**
  * Helper functionality to make working with IO easier.
  */
 library io;
 
 import 'dart:io';
@@ skipping 481 matching lines @@
   if ((Platform.operatingSystem == "windows") &&
       (executable.indexOf('\\') == -1)) {
     args = flatten(["/c", executable, args]);
     executable = "cmd";
   }
 
   final options = new ProcessOptions();
   if (workingDir != null) {
     options.workingDirectory = _getDirectory(workingDir).path;
   }
-  options.environment = environment;
+
+  if (environment != null) {
+    options.environment = environment;
+  }
 
   var future = Process.run(executable, args, options);
   return future.transform((result) {
     // TODO(rnystrom): Remove this and change to returning one string.
     List<String> toLines(String output) {
       var lines = output.split(NEWLINE_PATTERN);
       if (!lines.isEmpty && lines.last == "") lines.removeLast();
       return lines;
     }
     return new PubProcessResult(toLines(result.stdout),
@@ skipping 36 matching lines @@
   if (_isGitInstalledCache != null) {
     // TODO(rnystrom): The sleep is to pump the message queue. Can use
     // Future.immediate() when #3356 is fixed.
     return sleep(0).transform((_) => _isGitInstalledCache);
   }
 
   return _gitCommand.transform((git) => git != null);
 }
 
 /// Run a git process with [args] from [workingDir].
-Future<PubProcessResult> runGit(List<String> args, {String workingDir}) =>
-    _gitCommand.chain((git) => runProcess(git, args, workingDir: workingDir));
+Future<PubProcessResult> runGit(List<String> args,
+    {String workingDir, Map<String, String> environment}) {
+  return _gitCommand.chain((git) => runProcess(git, args,
+        workingDir: workingDir, environment: environment));
+}
 
 /// Returns the name of the git command-line app, or null if Git could not be
 /// found on the user's PATH.
 Future<String> get _gitCommand {
   // TODO(nweiz): Just use Future.immediate once issue 3356 is fixed.
   if (_gitCommandCache != null) {
     return sleep(0).transform((_) => _gitCommandCache);
   }
 
   return _tryGitCommand("git").chain((success) {
@@ skipping 177 matching lines @@
   return new Directory(entry);
 }
 
 /**
  * Gets a [Uri] for [uri], which can either already be one, or be a [String].
  */
 Uri _getUri(uri) {
   if (uri is Uri) return uri;
   return new Uri.fromString(uri);
 }