fix sftp option for scp

The option to use sftp was added multiple times when using
SSHDriver::put() and SSHDriver::get() causing them to only work one
time. Also adds the sftp option to SSHDriver::scp().

Signed-off-by: Nikolaj Rahbek <nikolaj@b2vn.org>
[bst: cherry-picked from commit c0016b0]
Signed-off-by: Bastian Krause <bst@pengutronix.de>

Author: Rahbek, Nikolaj (EXT) (SGRE OF TE TD LC SLC CMI)

CHANGES.rst

@@ -13,7 +13,6 @@ Bug fixes in 23.0.1
   ERROR, INFO and similar log notifiers.
 - Fix named SSH lookups in conjunction with an environment file in
   labgrid-client.
-  
 
 Release 23.0 (Released Apr 24, 2023)
 ------------------------------------

labgrid/driver/sshdriver.py

@@ -328,6 +328,10 @@ def scp(self, *, src, dst):
                 "-o", f"ControlPath={self.control.replace('%', '%%')}",
                 src, dst,
         ]
+        
+        if self.explicit_sftp_mode and self._scp_supports_explicit_sftp_mode():
+            complete_cmd.insert(1, "-s")
+
         self.logger.info("Running command: %s", complete_cmd)
         sub = subprocess.Popen(
             complete_cmd,
@@ -415,18 +419,18 @@ def _scp_supports_explicit_sftp_mode(self):
     @Driver.check_active
     @step(args=['filename', 'remotepath'])
     def put(self, filename, remotepath=''):
-        ssh_prefix = self.ssh_prefix
-        if self.explicit_sftp_mode and self._scp_supports_explicit_sftp_mode():
-            ssh_prefix.append("-s")
         transfer_cmd = [
             "scp",
-            *ssh_prefix,
+            *self.ssh_prefix,
             "-P", str(self.networkservice.port),
             "-r",
             filename,
             f"{self.networkservice.username}@{self.networkservice.address}:{remotepath}"
             ]
 
+        if self.explicit_sftp_mode and self._scp_supports_explicit_sftp_mode():
+            transfer_cmd.insert(1, "-s")
+
         try:
             sub = subprocess.call(
                 transfer_cmd
@@ -443,18 +447,18 @@ def put(self, filename, remotepath=''):
     @Driver.check_active
     @step(args=['filename', 'destination'])
     def get(self, filename, destination="."):
-        ssh_prefix = self.ssh_prefix
-        if self.explicit_sftp_mode and self._scp_supports_explicit_sftp_mode():
-            ssh_prefix.append("-s")
         transfer_cmd = [
             "scp",
-            *ssh_prefix,
+            *self.ssh_prefix,
             "-P", str(self.networkservice.port),
             "-r",
             f"{self.networkservice.username}@{self.networkservice.address}:{filename}",
             destination
             ]
 
+        if self.explicit_sftp_mode and self._scp_supports_explicit_sftp_mode():
+            transfer_cmd.insert(1, "-s")
+
         try:
             sub = subprocess.call(
                 transfer_cmd