Add a bunch of ugly debugging prints to figure out why the bots are failing.

pkg/scheduled_test/lib/scheduled_process.dart

 // Copyright (c) 2013, 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 scheduled_process;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'scheduled_test.dart';
@@ skipping 136 matching lines @@
 
   /// Listens for [_process] to exit and passes the exit code to
   /// [exitCodeCompleter]. If the process completes earlier than expected, an
   /// exception will be signaled to the schedule.
   void _handleExit(Completer exitCodeCompleter) {
     // We purposefully avoid using wrapFuture here. If an error occurs while a
     // process is running, we want the schedule to move to the onException
     // queue where the process will be killed, rather than blocking the tasks
     // queue waiting for the process to exit.
     _process.then((p) => p.exitCode).then((exitCode) {
+      print("[$description] exitCode completed with value '$exitCode'");
       if (_endExpected) {
+        print("[$description] expected the process to end, passing '$exitCode' to completer");
         exitCodeCompleter.complete(exitCode);
         return;
+      } else {
+        print("[$description] did not expect the process to end, maybe we should wait for the current task to end");
       }
 
       wrapFuture(pumpEventQueue().then((_) {
-        if (currentSchedule.currentTask != _taskBeforeEnd) return;
+        if (currentSchedule.currentTask != _taskBeforeEnd) {
+          print("[$description] not waiting for the current task to end");
+          return;
+        }
+        print("[$description] waiting for current task to end to see if the end will be expected");
         // If we're one task before the end was scheduled, wait for that task
         // to complete and pump the event queue so that _endExpected will be
         // set.
         return _taskBeforeEnd.result.then((_) => pumpEventQueue());
       }).then((_) {
+        print("[$description] passing '$exitCode' to completer");
         exitCodeCompleter.complete(exitCode);
 
         if (!_endExpected) {
+          print("[$description] end not expected, throwing error");
           throw "Process '${this.description}' ended earlier than scheduled "
             "with exit code $exitCode.";
+        } else {
+          print("[$description] end expected, not throwing error");
         }
       }));
     });
   }
 
   /// Converts a stream of bytes to a stream of lines and returns that along
   /// with a [StreamSubscription] controlling it.
   Pair<Stream<String>, StreamSubscription<String>> _lineStreamWithSubscription(
       Future<Stream<int>> streamFuture) {
     return streamWithSubscription(futureStream(streamFuture)
         .handleError((e) => currentSchedule.signalError(e))
         .transform(new StringDecoder(_encoding))
         .transform(new LineTransformer()));
   }
 
   /// Schedule an exception handler that will clean up the process and provide
   /// debug information if an error occurs.
   void _scheduleExceptionCleanup() {
     currentSchedule.onException.schedule(() {
+      print("[$description] cleaning up after exception");
       _stdoutSubscription.cancel();
       _stderrSubscription.cancel();
 
       if (!_process.hasValue) return;
 
       var killedPrematurely = false;
       if (!_exitCode.hasValue) {
+        print("[$description] exit code has not been set, killing process");
         var killedPrematurely = true;
         _endExpected = true;
         _process.value.kill();
         // Ensure that the onException queue waits for the process to actually
         // exit after being killed.
         wrapFuture(_process.value.exitCode);
+      } else {
+        print("[$description] exit code has been set to '${_process.value.exitCode.value}', process is dead");
       }
 
       return Future.wait([
         _stdoutLog.toList(),
         _stderrLog.toList()
       ]).then((results) {
+        print("[$description] got stdout/stderr, killedPrematurely=$killedPrematurely, exitCode.value=${_exitCode.value}");
         var stdout = results[0].join("\n");
         var stderr = results[1].join("\n");
 
         var exitDescription = killedPrematurely
             ? "Process was killed prematurely."
             : "Process exited with exit code ${_exitCode.value}.";
         currentSchedule.addDebugInfo(
             "Results of running '${this.description}':\n"
             "$exitDescription\n"
             "Standard output:\n"
@@ skipping 75 matching lines @@
     schedule(() {
       _endExpected = true;
       return _exitCode.then((exitCode) {
         if (expectedExitCode != null) {
           expect(exitCode, equals(expectedExitCode));
         }
       });
     }, "waiting for process '$description' to exit");
   }
 }