Add a bunch of extra logging to Pub.

sdk/lib/_internal/pub/lib/src/hosted_source.dart

Index: sdk/lib/_internal/pub/lib/src/hosted_source.dart
diff --git a/sdk/lib/_internal/pub/lib/src/hosted_source.dart b/sdk/lib/_internal/pub/lib/src/hosted_source.dart
index 17b18399cb209e16c3066aa69418202f37d0c0f0..194b6e0cd6ff435b13aee5d365e98c3e3953f452 100644
--- a/sdk/lib/_internal/pub/lib/src/hosted_source.dart
+++ b/sdk/lib/_internal/pub/lib/src/hosted_source.dart
@@ -36,10 +36,13 @@ class HostedSource extends Source {
 
     log.io("Get versions from $url.");
     return httpClient.read(url).then((body) {
+      log.io("Versions JSON from $url: $body.");
       var doc = json.parse(body);
-      return doc['versions']
+      var versions = doc['versions']
           .map((version) => new Version.parse(version))
           .toList();
+      log.io("Versions from $url: $versions.");
+      return versions;
     }).catchError((ex) {
       var parsed = _parseDescription(description);
       _throwFriendlyError(ex, parsed.first, parsed.last);