address chapter13 update review comments

move commit, add TIP. Also, fix code listing and spacing.
Make 'broken code listing id-s' an Issue on GitHub

Author: Xronophobe

chapter_13_database_layer_validation.asciidoc

@@ -580,13 +580,28 @@ Not quite, but they did get a little further.  Checking the line in which the
 error occurred -- 'line 31' in my case -- , we can
 // CSANAD: I think emphasizing what to look for in the error log is helpful.
 see that we've got past the first part of the test, and are now onto the second
-check--that submitting a second empty item also shows an error.
+check -- that submitting a second empty item also shows an error.
 
 ((("", startref="MLVsurfac13")))We've
-got some working code though, so let's put an early return in the FT to separate
+got some working code though, so let's have a commit:
+
+
+[subs="specialcharacters,quotes"]
+----
+$ *git commit -am "Adjust new list view to do model validation"*
+----
+
+
+TIP: When working on a new feature, it's common to realize partway through that
+    a refactor of the application is needed. Adding an early return to the FT
+    you're currently working on allows you to perform this refactor against
+    passing FTs, even while the feature is still in progress.
+
+
+Let's put an early return in the FT to separate
 what we got working from those that still need to be dealt with:
+
 [role="sourcecode"]
-// TODO fix code listing reference number
 .src/functional_tests/test_list_item_validation.py (ch13l???)
 ====
 [source,python]
@@ -603,6 +618,7 @@ class ItemValidationTest(FunctionalTest):
         # Perversely, she now decides to submit a second blank list item
         self.browser.find_element(By.ID, "id_new_item").send_keys(Keys.ENTER)
         [...]
+----
 ====
 
 
@@ -615,16 +631,7 @@ We should also remind ourselves not to forget to remove this early return:
 * 'Remove the early return from the FT'
 *****
 
-...and it's time to commit our changes:
-
-
-[subs="specialcharacters,quotes"]
-----
-$ *git commit -am "Adjust new list view to do model validation"*
-----
-
-
-
+And now, we can focus on making our code a little neater.
 
 
 === Django Pattern: Processing POST Requests in the Same View as Renders the Form
@@ -831,7 +838,17 @@ OK
 ----
 
 
-Let's try a full FT run: they're all passing! We can remove the early return
+Let's try a full FT run: they're all passing!
+Our refactor of the `add_item` functionality is complete.
+We should commit there:
+
+[subs="specialcharacters,quotes"]
+----
+$ *git commit -am "Refactor list view to handle new item POSTs"*
+----
+
+
+We can remove the early return
 now.
 
 [role="scratchpad"]
@@ -857,13 +874,6 @@ FAILED (errors=1)
 ----
 
 We're back to the one failure in our new functional test.
-Our refactor of the `add_item` functionality is complete.
-We should commit there:
-
-[subs="specialcharacters,quotes"]
-----
-$ *git commit -am "Refactor list view to handle new item POSTs"*
-----