Report wrapped pub exceptions with --verbose and --trace.

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

Index: sdk/lib/_internal/pub/lib/src/http.dart
diff --git a/sdk/lib/_internal/pub/lib/src/http.dart b/sdk/lib/_internal/pub/lib/src/http.dart
index f9e63bbb8590eb0eb5f95e8130a1932d1b80514b..af289fc37d39456b626d866e455d186d7cbbe324 100644
--- a/sdk/lib/_internal/pub/lib/src/http.dart
+++ b/sdk/lib/_internal/pub/lib/src/http.dart
@@ -85,7 +85,7 @@ class PubHttpClient extends http.BaseClient {
       return http.Response.fromStream(streamedResponse).then((response) {
         throw new PubHttpException(response);
       });
-    }).catchError((error) {
+    }).catchError((error, stackTrace) {
       if (error is SocketException &&
           error.osError != null) {
         if (error.osError.errorCode == 8 ||
@@ -93,10 +93,12 @@ class PubHttpClient extends http.BaseClient {
             error.osError.errorCode == -5 ||
             error.osError.errorCode == 11001 ||
             error.osError.errorCode == 11004) {
-          fail('Could not resolve URL "${request.url.origin}".');
+          fail('Could not resolve URL "${request.url.origin}".',
+              error, stackTrace);
         } else if (error.osError.errorCode == -12276) {
           fail('Unable to validate SSL certificate for '
-              '"${request.url.origin}".');
+              '"${request.url.origin}".',
+              error, stackTrace);
         }
       }
       print('Error in PubHttpClient.send (issue 12581) error: $error');