When pub 'serve' dies, it hangs on to the port

[mit-mit]

From @irfantusneem on June 18, 2015 16:53

Virtual file system is no longer available so pub crashes. When it makes you think it crashed, it is still running in the background on linux and holding on to the port. I need to manually kill the process so I can run it again.

Unhandled exception:
Uncaught Error: FileSystemException: Cannot open file, path = 'users//irfan/mywork/manifest.rawproto' (OS Error: No such file or directory, errno = 2)
Stack Trace:
#0 _File.open. (dart:io/file_impl.dart:353)
#1 _RootZone.runUnary (dart:async/zone.dart:1166)
#2 _Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:494)
#3 _Future._propagateToListeners (dart:async/future_impl.dart:577)
#4 _Future._completeWithValue (dart:async/future_impl.dart:368)
#5 _Future._asyncComplete. (dart:async/future_impl.dart:422)
#6 _microtaskLoop (dart:async/schedule_microtask.dart:43)
#7 _microtaskLoopEntry (dart:async/schedule_microtask.dart:52)
#8 _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:96)
#9 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:149)
#0 _rootHandleUncaughtError. (dart:async/zone.dart:895)
#1 _microtaskLoop (dart:async/schedule_microtask.dart:43)
#2 _microtaskLoopEntry (dart:async/schedule_microtask.dart:52)
#3 _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:96)
#4 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:149)

Copied from original issue: dart-lang/sdk#23673

[cbracken]

Verified that this is a Google-internal issue; fixed.