TTS - DevFailed on GetAttDefinitionData

When using TTS (db='T'), a DevFailed is returned by the extractor on command GetAttDefinitionData This exception is not catched.

In [7]: AE.extract('ANS-C16/DG/MESUREPURETE/countRate', '1m', db='T')
ArchiveExtractor-DEBUG   : Parsing date string '1m'
ArchiveExtractor-DEBUG   : Assuming a duration
ArchiveExtractor-DEBUG   : Check that ans-c16/dg/mesurepurete/countrate is archived.
ArchiveExtractor-DEBUG   : Exception in _extract_attribute(): DevFailed[
DevError[
    desc = fr.soleil.tango.archiving.exception.TangoTimeseriesException
  origin = fr.soleil.tango.archiving.exception.TangoTimeseriesException: not supported function
	at org.tango.archiving.server.extractor.TimeseriesAccess.getAttDefinitionData(TimeseriesAccess.java:88)
	at org.tango.archiving.server.extractor.HdbExtractor.getAttDefinitionData(HdbExtractor.java:202)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.tango.server.command.ReflectCommandBehavior.execute(ReflectCommandBehavior.java:63)
	at org.tango.server.command.CommandImpl.execute(CommandImpl.java:87)
	at org.tango.server.servant.DeviceImpl.commandHandler(DeviceImpl.java:1586)
	at org.tango.server.servant.DeviceImpl.command_inout_4(DeviceImpl.java:1453)
	at fr.esrf.Tango.Device_5POA._invoke(Device_5POA.java:228)
	at org.jacorb.poa.RequestProcessor.invokeOperation(RequestProcessor.java:402)
	at org.jacorb.poa.RequestProcessor.process(RequestProcessor.java:726)
	at org.jacorb.poa.RequestProcessor.run(RequestProcessor.java:884)

  reason = NA
severity = PANIC]

DevError[
    desc = Failed to execute command_inout on device tango/ca-tts/extractor_dg.1, command GetAttDefinitionData
  origin = Connection::command_inout()
  reason = API_CommandFailed
severity = ERR]
]
  File "/home/operateur/.local/lib/python3.6/site-packages/ArchiveExtractor/Access.py", line 197, in extract
    d=aec._extract_attribute(attr, method, date1, date2, db)
  File "/home/operateur/.local/lib/python3.6/site-packages/ArchiveExtractor/Core.py", line 26, in _extract_attribute
    info=ae.infoattr(attribute, db=db)
  File "/home/operateur/.local/lib/python3.6/site-packages/ArchiveExtractor/Access.py", line 270, in infoattr
    R=getattr(ae._Extractors[{'H':0, 'T':1}[db]], func)(attribute)
  File "/usr/Local/pyroot/PyTango3Root/lib/python3.6/site-packages/pytango-9.2.2-py3.6-linux-i686.egg/tango/device_proxy.py", line 230, in f
    return dp.command_inout(name, *args, **kwds)
  File "/usr/Local/pyroot/PyTango3Root/lib/python3.6/site-packages/pytango-9.2.2-py3.6-linux-i686.egg/tango/green.py", line 182, in greener
    return executor.run(fn, args, kwargs, wait=wait, timeout=timeout)
  File "/usr/Local/pyroot/PyTango3Root/lib/python3.6/site-packages/pytango-9.2.2-py3.6-linux-i686.egg/tango/green.py", line 96, in run
    return fn(*args, **kwargs)
  File "/usr/Local/pyroot/PyTango3Root/lib/python3.6/site-packages/pytango-9.2.2-py3.6-linux-i686.egg/tango/connection.py", line 104, in __Connection__command_inout
    r = Connection.command_inout_raw(self, name, *args, **kwds)
  File "/usr/Local/pyroot/PyTango3Root/lib/python3.6/site-packages/pytango-9.2.2-py3.6-linux-i686.egg/tango/connection.py", line 133, in __Connection__command_inout_raw
    return self.__command_inout(cmd_name, param)
ArchiveExtractor-DEBUG   : None
ArchiveExtractor-ERROR   : Could not extract ANS-C16/DG/MESUREPURETE/countRate.