Make pub use the SDK's "version" file for its version.

utils/pub/sdk.dart

Index: utils/pub/sdk.dart
diff --git a/utils/pub/sdk.dart b/utils/pub/sdk.dart
index f8db76c173ca4c1a0dc2090b8ae178d5c9ccd560..0365aab30e398ec9fb52a8065c57aac624116b75 100644
--- a/utils/pub/sdk.dart
+++ b/utils/pub/sdk.dart
@@ -11,6 +11,11 @@ import '../../pkg/path/lib/path.dart' as path;
 import 'log.dart' as log;
 import 'version.dart';
 
+/// Matches an Eclipse-style SDK version number. This is four dotted numbers
+/// (major, minor, patch, build) with an optional suffix attached to the build
+/// number.
+final _versionPattern = new RegExp(r'^(\d+)\.(\d+)\.(\d+)\.(\d+)(.*)$');
+
 /// Gets the path to the root directory of the SDK.
 String get rootDirectory {
   // If the environment variable was provided, use it. This is mainly used for
@@ -30,9 +35,23 @@ String get rootDirectory {
 /// Gets the SDK's revision number formatted to be a semantic version.
 Version version = _getVersion();
 
-/// Determine the SDK revision number.
+/// Determine the SDK's version number.
 Version _getVersion() {
-  var revisionPath = path.join(rootDirectory, "revision");
-  var revision = new File(revisionPath).readAsStringSync();
-  return new Version.parse("0.0.0-r.${revision.trim()}");
+  var revisionPath = path.join(rootDirectory, "version");
+  var version = new File(revisionPath).readAsStringSync().trim();
+
+  // Given a version file like: 0.1.2.0_r17495
+  // We create a semver like:   0.1.2+0._r17495
+  var match = _versionPattern.firstMatch(version);
+  if (match == null) {
+    throw new FormatException("The Dart SDK's 'version' file was not in a "
+        "format pub could recognize. Found: $revision");
+  }
+
+  var build = match[4];
+  if (match[5].length > 0) build = '$build.${match[5]}';
+
+  return new Version(
+      int.parse(match[1]), int.parse(match[2]), int.parse(match[3]),
+      build: build);
 }