React gracefully to a fully-.gitignored package.

lib/src/git.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 for invoking Git.
 library pub.git;
 
 import 'dart:async';
 import 'dart:io';
 
@@ skipping 16 matching lines @@
 
   GitException(Iterable<String> args, this.stderr)
       : args = args.toList();
 
   String toString() => message;
 }
 
 /// Tests whether or not the git command-line app is available for use.
 bool get isInstalled {
   if (_isInstalledCache != null) return _isInstalledCache;
-  _isInstalledCache = _gitCommand != null;
+  _isInstalledCache = command != null;
   return _isInstalledCache;
 }
 bool _isInstalledCache;
 
 /// Run a git process with [args] from [workingDir].
 ///
 /// Returns the stdout as a list of strings if it succeeded. Completes to an
 /// exception if it failed.
 Future<List<String>> run(List<String> args,
     {String workingDir, Map<String, String> environment}) {
   if (!isInstalled) {
     fail("Cannot find a Git executable.\n"
         "Please ensure Git is correctly installed.");
   }
 
   log.muteProgress();
-  return runProcess(_gitCommand, args, workingDir: workingDir,
+  return runProcess(command, args, workingDir: workingDir,
       environment: environment).then((result) {
     if (!result.success) throw new GitException(args, result.stderr.join("\n"));
 
     return result.stdout;
   }).whenComplete(() {
     log.unmuteProgress();
   });
 }
 
 /// Like [run], but synchronous.
 List<String> runSync(List<String> args, {String workingDir,
     Map<String, String> environment}) {
   if (!isInstalled) {
     fail("Cannot find a Git executable.\n"
         "Please ensure Git is correctly installed.");
   }
 
-  var result = runProcessSync(_gitCommand, args,
+  var result = runProcessSync(command, args,
       workingDir: workingDir,
       environment: environment);
   if (!result.success) throw new GitException(args, result.stderr.join("\n"));
   return result.stdout;
 }
 
 /// Starts a git process and returns it.
 Future<PubProcess> start(List<String> args,
     {String workingDir, Map<String, String> environment}) {
   if (!isInstalled) {
     fail("Cannot find a Git executable.\n"
         "Please ensure Git is correctly installed.");
   }
 
-  return startProcess(_gitCommand, args, workingDir: workingDir,
+  return startProcess(command, 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.
-String get _gitCommand {
+String get command {
   if (_commandCache != null) return _commandCache;
 
   var command;
   if (_tryGitCommand("git")) {
     _commandCache = "git";
   } else if (_tryGitCommand("git.cmd")){
     _commandCache = "git.cmd";
   } else {
     return null;
   }
@@ skipping 10 matching lines @@
     var result = runProcessSync(command, ["--version"]);
     var regexp = new RegExp("^git version");
     return result.stdout.length == 1 && regexp.hasMatch(result.stdout.single);
   } on ProcessException catch (error, stackTrace) {
     var chain = new Chain.forTrace(stackTrace);
     // If the process failed, they probably don't have it.
     log.error('Git command is not "$command": $error\n$chain');
     return false;
   }
 }