Bring in the latest pub.

CHANGELOG.md

 ## 1.14.0
 
 ### Core library changes
 * `dart:convert`
   * `Base64Decoder.convert` now takes optional `start` and `end` parameters.
 
 * `dart:core`
   * Added `current` getter to `StackTrace` class.
   * Added `Uri.data` getter for `data:` URIs, and `UriData` class for the
     return type.
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     to real-world use-cases.
 
   * `pub deps` now supports a `--no-dev` flag, which causes it to emit the
     dependency tree as it would be if no `dev_dependencies` were in use. This
     makes it easier to see your package's dependency footprint as your users
     will experience it.
 
   * `pub global run` now detects when a global executable's SDK constraint is no
     longer met and errors out, rather than trying to run the executable anyway.
 
+  * Pub commands that check whether the lockfile is up-to-date (`pub run`, `pub
+    deps`, `pub serve`, and `pub build`) now do additional verification. They
+    ensure that any path dependencies' pubspecs haven't been changed, and they
+    ensure that the current SDK version is compatible with all dependencies.
+
   * Fixed a crashing bug when using `pub global run` on a global script that
     didn't exist.
 
   * Fixed a crashing bug when a pubspec contains a dependency without a source
     declared.
 
 ## 1.13.0 - 2015-11-18
 
 ### Core library changes
 * `dart:async`
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     they will keep the Dart process alive until they time out. This fixes the
     handling of persistent connections. Previously, the client would shut down
     immediately after a request.
 
   * **Breaking change:** `HttpServer` no longer compresses all traffic by
     default. The new `autoCompress` property can be set to `true` to re-enable
     compression.
 
 * `dart:isolate`: `Isolate.spawnUri` added the optional `packageRoot` argument,
   which controls how it resolves `package:` URIs.