ID 351749 - Various export tasks (e.g. the EDLExportTask) will not trigger callbacks for startTask

Problem summary
Various export tasks (e.g. the EDLExportTask) will not trigger callbacks for startTask. 
All derived classes should call the base class versions of both the startTask and finishTask functions.

Steps to reproduce

1) Open Nuke Studio.

2) Open the Script Editor panel.

3) Execute the following python script in the editor:

from hiero.core.FnExporterBase import TaskCallbacks

def onTaskFinish(arg):
  print arg
  print "Task Finished"

def onTaskStart(arg):
  print arg
  print "Task Started"

TaskCallbacks.addCallback(TaskCallbacks.onTaskFinish, onTaskFinish)
TaskCallbacks.addCallback(TaskCallbacks.onTaskStart, onTaskStart

This will add start and finish export task callbacks.

4) Import a clip into the bin.

5) Drag that clip on to the Timeline.

6) Right click the sequence in the bin and select "Export".

7) Select "Process as Sequence" -> "CMX 3600 EDL" 

8) Click "Export"

9) An EDLExportTask should run. This can be seen in the Export Queue.

10) The output in the script editor will look similar to the following:

<hiero.exporters.FnEDLExportTask.EDLExportTask object at 0x11d3cbd88>

Task Finished

This is incorrect. Only the finished callback is triggered. The start callback is missing.


Reproduced by support
This bug has been reproduced by the developers.


Expected behaviour
All derived classes should call the base class versions of both the startTask and finishTask functions. The following steps demonstrate the correct behaviour:

1) Open Nuke Studio.

2) Open the Script Editor panel.

3) Execute the following python script in the editor:

from hiero.core.FnExporterBase import TaskCallbacks

def onTaskFinish(arg):
  print arg
  print "Task Finished"

def onTaskStart(arg):
  print arg
  print "Task Started"

TaskCallbacks.addCallback(TaskCallbacks.onTaskFinish, onTaskFinish)
TaskCallbacks.addCallback(TaskCallbacks.onTaskStart, onTaskStart

This will add start and finish export task callbacks.

4) Import a clip into the bin.

5) Drag that clip to a sequence.

6) Right click the sequence in the bin and select "Export".

7) Right click the sequence in the bin and select "Export".

8) Select "Process as Shots" -> "Basic Nuke Shot" as the preset.

9) Click "Export".

10) A NukeShotExporterTask and a NukeRenderTask should run. These can be seen in the Export Queue.

The output in the script editor should look something like the following:

<hiero.exporters.FnNukeShotExporter.NukeShotExporter object at 0x128fa91b8>
Task Started
<hiero.exporters.FnNukeShotExporter.NukeShotExporter object at 0x128fa91b8>
Task Finished
<hiero.exporters.FnExternalRender.NukeRenderTask object at 0x1283f4cf8>
Task Started
<hiero.exporters.FnExternalRender.NukeRenderTask object at 0x1283f4cf8>
Task Finished

Actual behaviour
Various export tasks (e.g. the EDLExportTask) will not trigger callbacks for startTask.