driver: SigrokDriver unsuccessful sigrok-cli termination when used remotely

the signal that is supposed to terminate the process SIGINT was not being propagated through ssh.
The driver waited for termination forever.

fixed by quitting sigrok-cli through an emulated keypress by sending a char over ssh.

Signed-off-by: Felix Zwettler <Felix.Zwettler@duagon.com>

Author: flxzt

labgrid/driver/sigrokdriver.py

@@ -2,7 +2,6 @@
 import re
 import subprocess
 import shutil
-import signal
 import tempfile
 import time
 import uuid
@@ -171,8 +170,8 @@ def stop(self):
         fnames.extend(self.sigrok.channels.split(','))
         csv_filename = f'{os.path.splitext(self._basename)[0]}.csv'
 
-        self._process.send_signal(signal.SIGINT)
-        stdout, stderr = self._process.communicate()
+        # sigrok-cli can be quit through any keypress
+        stdout, stderr = self._process.communicate(input="q")
         self.logger.debug("stdout: %s", stdout)
         self.logger.debug("stderr: %s", stderr)