faft: log servo_host os version

Log the servo host os version, so we can track what labstation version
we're running more easily.

BUG=none
BRANCH=none
TEST=none

Change-Id: I89750b795c207b37a43a9b69b13e15daeccc9cb5
Signed-off-by: Mary Ruthven <mruthven@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1679712
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Wai-Hong Tam <waihong@google.com>
diff --git a/server/cros/servo/servo.py b/server/cros/servo/servo.py
index 10d205d..da4b2c0 100644
--- a/server/cros/servo/servo.py
+++ b/server/cros/servo/servo.py
@@ -13,6 +13,7 @@
 import xmlrpclib
 
 from autotest_lib.client.common_lib import error
+from autotest_lib.client.common_lib import lsbrelease_utils
 from autotest_lib.server import utils as server_utils
 from autotest_lib.server.cros.servo import firmware_programmer
 
@@ -342,6 +343,14 @@
         return self._servo_host.is_localhost()
 
 
+    def get_os_version(self):
+        """Returns the chromeos release version."""
+        lsb_release_content = self.system_output('cat /etc/lsb-release',
+                                                 ignore_status=True)
+        return lsbrelease_utils.get_chromeos_release_builder_path(
+                    lsb_release_content=lsb_release_content)
+
+
     def power_long_press(self):
         """Simulate a long power button press."""
         # After a long power press, the EC may ignore the next power