fix: adapt to napalm-device-types 4.7

napalm-device-types 4.7 changed three things this driver depends on:

- parse_dnf_security needs the "__DNF_RC=<status>" line that
  DNF_SECURITY_COMMAND prints and raises ValueError without it or when dnf
  failed. The yum security query had no such line, so listing updates on
  any yum host raised. _YUM_SECURITY_COMMAND now prints the marker the same
  way ("{ ...; echo __DNF_RC=$?; } | cat"). _rpm_security_names checks
  __DNF_RC itself and turns a failed query, or output cut short before the
  marker, into None (security unknown) rather than "no advisories" or an
  exception.
- OSDriver.get_users was renamed to get_os_users, since NAPALM's own
  get_users has another shape. LinuxDriver.get_users is now get_os_users
  with the same return value.
- run_on_transport reads an exec channel to EOF after its exit status
  arrives; the tests' fake channels gain recv/recv_stderr for that.

Require napalm-device-types>=4.7.1 and bump the version to 0.6.0.

napalm_linux/linux.py

@@ -125,7 +125,14 @@ _REFRESH = {
     "yum": "yum makecache -q 2>&1",
     "apk": "apk update -q 2>&1",
 }
-_YUM_SECURITY_COMMAND = "LC_ALL=C yum updateinfo list security -q 2>/dev/null"
+#: yum's counterpart of DNF_SECURITY_COMMAND, in the same shape: parse_dnf_security
+#: (napalm-device-types 4.7) needs the ``__DNF_RC=`` line, and behind ``| cat`` it is
+#: the only place yum's own exit status survives.
+_YUM_SECURITY_COMMAND = (
+    "{ LC_ALL=C yum updateinfo list security -q 2>/dev/null; echo __DNF_RC=$?; } | cat"
+)
+#: The exit status ``DNF_SECURITY_COMMAND`` and ``_YUM_SECURITY_COMMAND`` report.
+_DNF_RC_RE = re.compile(r"^__DNF_RC=(\d+)\s*$", re.MULTILINE)
 
 #: Restart the host two seconds later, detached from this session: the launcher's
 #: exit status comes back before the host goes down, and closing the session
@@ -1512,7 +1519,16 @@ class LinuxDriver(
         """Packages a pending security advisory covers; None when dnf/yum cannot say."""
         cmd = DNF_SECURITY_COMMAND if self._pkg_manager == "dnf" else _YUM_SECURITY_COMMAND
         output, status = _split_status(self._run_privileged(f"{cmd}; echo {_RC_MARKER}$?", 120))
-        return parse_dnf_security(output) if status == 0 else None
+        # Both commands pipe through cat, so the outer status is cat's: dnf/yum's own
+        # is in __DNF_RC. A failed run prints nothing on stdout and must not read as
+        # "no advisories"; neither may output cut short before the marker.
+        rc = _DNF_RC_RE.findall(output)
+        if status != 0 or not rc or rc[-1] != "0":
+            return None
+        try:
+            return parse_dnf_security(output)
+        except ValueError:
+            return None
 
     def refresh_available_updates(self) -> dict[str, Any]:
         """Refresh the package index (apt-get update, dnf makecache, apk update)."""
@@ -1695,7 +1711,7 @@ class LinuxDriver(
     # OSDriver – users
     # ------------------------------------------------------------------
 
-    def get_users(self) -> list[UserDict]:
+    def get_os_users(self) -> list[UserDict]:
         """Return local user accounts from /etc/passwd plus supplementary groups."""
         passwd_out = self._send("getent passwd 2>/dev/null || cat /etc/passwd")
         groups_out = self._send("getent group 2>/dev/null || cat /etc/group")