Repository: obspy/obspy

Issue:
Seedlink client tests take very long, related error 'response: no data stream selector(s) accepted' logged
I think there might be some error in the seedlink class. The seedlink tests take very long and some error are logged:

```
(workhorse) eule@kiste:~/dev/obspy$ obspy-runtests --network clients/seedlink --durations=10 -rA -s
======= test session starts ========
platform linux -- Python 3.8.6, pytest-6.2.4, py-1.10.0, pluggy-0.13.1
rootdir: /home/eule/dev/obspy/obspy, configfile: pytest.ini
plugins: sphinx-0.3.1, html-3.1.1, cov-2.10.1, metadata-1.11.0, json-report-1.4.1
collected 13 items                                                                                                                                                                                                                           

clients/seedlink/basic_client.py ..
clients/seedlink/easyseedlink.py .
clients/seedlink/tests/test_basic_client.py ...
clients/seedlink/tests/test_seedlinkconnection.py .
clients/seedlink/tests/test_slclient.py sss
clients/seedlink/tests/test_slnetstation.py .
clients/seedlink/tests/test_slpacket.py .
clients/seedlink/tests/test_slstate.py .

============== PASSES ==============
_______________________________________________________________________________________ [doctest] obspy.clients.seedlink.basic_client.Client.get_info ________________________________________________________________________________________
------------------------------------------------------------------------------------------------------------- Captured log call --------------------------------------------------------------------------------------------------------------
ERROR     obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:850 negotiation with remote SeedLink failed: 'response: no data stream selector(s) accepted'
WARNING   obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:702 terminating collect loop
ERROR     obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:850 negotiation with remote SeedLink failed: 'response: no data stream selector(s) accepted'
WARNING   obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:702 terminating collect loop
_____________________________________________________________________________________ [doctest] obspy.clients.seedlink.basic_client.Client.get_waveforms _____________________________________________________________________________________
------------------------------------------------------------------------------------------------------------- Captured log call --------------------------------------------------------------------------------------------------------------
ERROR     obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:850 negotiation with remote SeedLink failed: 'response: no data stream selector(s) accepted'
WARNING   obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:702 terminating collect loop
ERROR     obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:850 negotiation with remote SeedLink failed: 'response: no data stream selector(s) accepted'
WARNING   obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:702 terminating collect loop
________________________________________________________________________________________________________ ClientTestCase.test_get_info ________________________________________________________________________________________________________
------------------------------------------------------------------------------------------------------------- Captured log call --------------------------------------------------------------------------------------------------------------
ERROR     obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:850 negotiation with remote SeedLink failed: 'response: no data stream selector(s) accepted'
WARNING   obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:702 terminating collect loop
______________________________________________________________________________________________________ ClientTestCase.test_get_waveform ______________________________________________________________________________________________________
------------------------------------------------------------------------------------------------------------- Captured log call --------------------------------------------------------------------------------------------------------------
ERROR     obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:850 negotiation with remote SeedLink failed: 'response: no data stream selector(s) accepted'
WARNING   obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:702 terminating collect loop
_________________________________________________________________________________ ClientTestCase.test_multiple_waveform_requests_with_multiple_info_requests _________________________________________________________________________________
------------------------------------------------------------------------------------------------------------- Captured log call --------------------------------------------------------------------------------------------------------------
ERROR     obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:850 negotiation with remote SeedLink failed: 'response: no data stream selector(s) accepted'
WARNING   obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:702 terminating collect loop
ERROR     obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:850 negotiation with remote SeedLink failed: 'response: no data stream selector(s) accepted'
WARNING   obspy.clients.seedlink [rtserver.ipgp.fr:18000]:seedlinkconnection.py:702 terminating collect loop
======= slowest 10 durations =======
41.17s call     clients/seedlink/basic_client.py::obspy.clients.seedlink.basic_client.Client.get_waveforms
40.44s call     clients/seedlink/basic_client.py::obspy.clients.seedlink.basic_client.Client.get_info
8.91s call     clients/seedlink/tests/test_basic_client.py::ClientTestCase::test_multiple_waveform_requests_with_multiple_info_requests
4.37s call     clients/seedlink/tests/test_basic_client.py::ClientTestCase::test_get_waveform
4.14s call     clients/seedlink/tests/test_basic_client.py::ClientTestCase::test_get_info

(5 durations < 0.005s hidden.  Use -vv to show these durations.)
===== short test summary info 
SKIPPED [1] clients/seedlink/tests/test_slclient.py:18: test must be started manually
SKIPPED [1] clients/seedlink/tests/test_slclient.py:40: test must be started manually
SKIPPED [1] clients/seedlink/tests/test_slclient.py:27: test must be started manually
================================================================================================== 10 passed, 3 skipped in 99.39s (0:01:39) ==================================================================================================


Discussion:

Resolving patch:
diff --git a/obspy/clients/seedlink/basic_client.py b/obspy/clients/seedlink/basic_client.py
--- a/obspy/clients/seedlink/basic_client.py
+++ b/obspy/clients/seedlink/basic_client.py
@@ -337,7 +337,7 @@ def _packet_handler(self, count, slpack):
             if self.debug:
                 print("Complete INFO:",
                       self._slclient.slconn.get_info_string())
-            return False
+            return True
 
         # process packet data
         trace = slpack.get_trace()


Test patch: