"pub global run" errors out for a mismatched SDK.

lib/src/global_packages.dart

 // Copyright (c) 2014, 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.
 
 library pub.global_packages;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:path/path.dart' as p;
@@ skipping 290 matching lines @@
       new File(oldLockFilePath).renameSync(lockFilePath);
     }
 
     // Remove the package itself from the lockfile. We put it in there so we
     // could find and load the [Package] object, but normally an entrypoint
     // doesn't expect to be in its own lockfile.
     var id = lockFile.packages[name];
     lockFile = lockFile.removePackage(name);
 
     var source = cache.sources[id.source];
+    var entrypoint;
     if (source is CachedSource) {
       // For cached sources, the package itself is in the cache and the
       // lockfile is the one we just loaded.
       var dir = cache.sources[id.source].getDirectory(id);
       var package = new Package.load(name, dir, cache.sources);
-      return new Entrypoint.inMemory(package, lockFile, cache, isGlobal: true);
+      entrypoint = new Entrypoint.inMemory(
+          package, lockFile, cache, isGlobal: true);
+    } else {
+      // For uncached sources (i.e. path), the ID just points to the real
+      // directory for the package.
+      assert(id.source == "path");
+      entrypoint = new Entrypoint(
+          PathSource.pathFromDescription(id.description), cache,
+          isGlobal: true);
     }
 
-    // For uncached sources (i.e. path), the ID just points to the real
-    // directory for the package.
-    assert(id.source == "path");
-    return new Entrypoint(
-        PathSource.pathFromDescription(id.description), cache, isGlobal: true);
+    if (entrypoint.root.pubspec.environment.sdkVersion.allows(sdk.version)) {
+      return entrypoint;
+    }
+
+    dataError("${log.bold(name)} ${entrypoint.root.version} doesn't support "
+        "Dart ${sdk.version}.");
   }
 
   /// Runs [package]'s [executable] with [args].
   ///
   /// If [executable] is available in its precompiled form, that will be
   /// recompiled if the SDK has been upgraded since it was first compiled and
   /// then run. Otherwise, it will be run from source.
   ///
   /// If [checked] is true, the program is run in checked mode. If [mode] is
   /// passed, it's used as the barback mode; it defaults to
@@ skipping 450 matching lines @@
   }
 
   /// Returns the value of the property named [name] in the bin stub script
   /// [source].
   String _binStubProperty(String source, String name) {
     var pattern = new RegExp(quoteRegExp(name) + r": ([a-zA-Z0-9_-]+)");
     var match = pattern.firstMatch(source);
     return match == null ? null : match[1];
   }
 }