Clarify "restart"

Without this patch, one might be confused by the meaning of
restart, and why we are doing actions twice.

This patch makes it clear that the method used to evaluate
if zypper should run twice is in fact dependent of zypper itself
and it's return code (not on some kind of obscure code output).
It should be easier to follow/review with this kind of wording.

skuba-update/skuba_update/skuba_update.py

@@ -111,10 +111,10 @@ def update():
     Performs an update operation.
     """
 
-    code = run_zypper_patch()
-    if is_restart_needed(code):
-        code = run_zypper_patch()
-    return code
+    returncode = run_zypper_patch()
+    if zypper_packagemanager_needs_restart(returncode):
+        returncode = run_zypper_patch()
+    return returncode
 
 
 def annotate_node():
@@ -249,10 +249,10 @@ def is_zypper_error(code):
     return code != 0 and code < ZYPPER_EXIT_INF_UPDATE_NEEDED
 
 
-def is_restart_needed(code):
+def zypper_packagemanager_needs_restart(code):
     """
-    Returns true of the given code is defined by zypper to mean that restart is
-    needed (zypper itself has been updated).
+    Returns true if the given return code by zypper means a restart
+    of zypper is needed (zypper itself has been updated).
     """
 
     return code == ZYPPER_EXIT_INF_RESTART_NEEDED
@@ -316,8 +316,8 @@ def run_zypper_command(command, needsOutput=False):
 
 def run_zypper_patch():
     """
-    Run patch updates without --with-optional. --with-optional can cause
-    conflicts with K8s upgrade scenario.
+    Install patch updates (zypper patch) without '--with-optional' flag.
+    --with-optional can cause conflicts with K8s upgrade scenario.
     """
     return run_zypper_command([
         '--non-interactive', '--non-interactive-include-reboot-patches',