fix: keep systemd's OSC 3008 shell context out of command output (#41)

Backport of the 0.15.1 fix onto 0ba5081, the commit netOrk pins, which
cannot take 0.15.x before it moves to napalm-device-types 4.22.

systemd 258 (Ubuntu 26.04) ships /etc/profile.d/80-systemd-osc-context.sh:
an interactive bash wraps every command in OSC 3008 sequences from PS0 and
PROMPT_COMMAND, each with a fresh UUID. They ended up in every value read
through netmiko's shell, and because the prompt never looked the same twice,
the prompt line stayed in the output too. os_version grew past 255
characters and netOrk could not store the poll.

The session now unsets PS0 and PROMPT_COMMAND right after switching the
history off and reads its prompt anew; _send() strips terminal codes from
what it returns.

tests/test_sudo_off_the_command_line.py

@@ -236,7 +236,8 @@ class TestHistoryOff:
     def test_a_shell_that_refuses_it_does_not_stop_the_connection(self):
         driver = LinuxDriver("h", "admin", "p")
         device = MagicMock()
-        device.send_command.side_effect = [Exception("no prompt"), "", "/usr/bin/apt"]
+        # history off (refused), prompt hooks off (#41), stty, package manager
+        device.send_command.side_effect = [Exception("no prompt"), "", "", "/usr/bin/apt"]
         with patch("napalm_linux.linux.ConnectHandler", return_value=device):
             driver.open()
 

tests/test_systemd_osc_context.py

@@ -0,0 +1,78 @@
+"""systemd's shell context sequences stay out of every command's output (#41).
+
+systemd 258 (Ubuntu 26.04) ships ``/etc/profile.d/80-systemd-osc-context.sh``.
+An interactive bash then wraps every command in OSC 3008 sequences, from ``PS0``
+before it runs and from ``PROMPT_COMMAND`` before the next prompt, each with a
+fresh UUID. netmiko's interactive shell is such a bash: the sequences ended up in
+every parsed value, and since the prompt never looked the same twice, netmiko
+left the prompt line in the output as well. ``os_version`` grew past 255
+characters and netOrk could not store the poll.
+"""
+
+from unittest.mock import MagicMock, patch
+
+from napalm_linux.linux import _HISTORY_OFF, _PROMPT_HOOKS_OFF, LinuxDriver
+
+#: What ``cat /etc/os-release | grep PRETTY_NAME ...`` returned through netmiko on
+#: an Ubuntu 26.04.1 host (2026-10-23), the prompt line already gone.
+_UBUNTU_2604_OS_RELEASE = (
+    "\x1b]3008;end=87c2e1c5-f850-4429-9f06-749e9be783e6;exit=success\x1b\\"
+    "\x1b]3008;start=bc3bc23b-2652-4826-8192-be447f97dd6f;type=command;"
+    "machineid=35cf42f3beb446bbb9aa95b937a0cf48;user=netork;hostname=ubuntu;"
+    "bootid=d32bd88c-dfce-40fe-9869-257bf50ef0e0;pid=20059;cwd=/home/netork\x1b\\"
+    "Ubuntu 26.04.1 LTS\n"
+)
+
+
+def _opened(device: MagicMock) -> LinuxDriver:
+    driver = LinuxDriver("h", "admin", "p")
+    with patch("napalm_linux.linux.ConnectHandler", return_value=device):
+        driver.open()
+    return driver
+
+
+class TestPromptHooksOff:
+    def test_the_session_drops_the_hooks_right_after_the_history(self):
+        device = MagicMock()
+        device.send_command.return_value = "/usr/bin/apt"
+
+        _opened(device)
+
+        sent = [c.args[0] for c in device.send_command.call_args_list]
+        assert sent[:2] == [_HISTORY_OFF, _PROMPT_HOOKS_OFF]
+
+    def test_it_unsets_both_hooks_including_an_array_prompt_command(self):
+        # The script appends to PROMPT_COMMAND as an array; assigning the empty
+        # string would only clear element 0 and leave systemd's hook running.
+        assert _PROMPT_HOOKS_OFF.startswith(" ")
+        assert "unset PS0 PROMPT_COMMAND" in _PROMPT_HOOKS_OFF
+
+    def test_the_prompt_is_read_again_once_the_hooks_are_gone(self):
+        # netmiko learned the prompt with the sequences in front of it; a prompt
+        # carrying a UUID never matches again, so strip_prompt would keep failing.
+        device = MagicMock()
+        device.send_command.return_value = "/usr/bin/apt"
+
+        _opened(device)
+
+        calls = [(c[0], c.args[0] if c.args else None) for c in device.mock_calls]
+        hooks_off = calls.index(("send_command", _PROMPT_HOOKS_OFF))
+        assert "set_base_prompt" in [name for name, _ in calls[hooks_off + 1 :]]
+
+    def test_a_shell_that_refuses_it_does_not_stop_the_connection(self):
+        device = MagicMock()
+        device.send_command.side_effect = ["", Exception("no prompt"), "", "/usr/bin/apt"]
+
+        driver = _opened(device)
+
+        assert driver._device is device
+
+
+class TestSendStripsTerminalCodes:
+    def test_os_version_comes_back_without_the_context_sequences(self):
+        device = MagicMock()
+        device.send_command.return_value = _UBUNTU_2604_OS_RELEASE
+        driver = LinuxDriver("h", "admin", "p")
+        driver._device = device
+
+        assert driver._send("cat /etc/os-release") == "Ubuntu 26.04.1 LTS"