Update Python style guide to point out exceptions only apply to legacy scripts

styleguide/styleguide.md

Index: styleguide/styleguide.md
diff --git a/styleguide/styleguide.md b/styleguide/styleguide.md
index 69e746bd9493c013be26cabc6b33d012be3cc85f..9fa42482d154f92abe2ff569cc518208a240556b 100644
--- a/styleguide/styleguide.md
+++ b/styleguide/styleguide.md
@@ -15,17 +15,15 @@ Chromium also uses these languages to a lesser degree:
 
 ## Python
 
-Python code should follow [PEP-8](https://www.python.org/dev/peps/pep-0008/),
-except:
+Python code should follow [PEP-8](https://www.python.org/dev/peps/pep-0008/).
+
+Some existing scripts were originally written following Google's internal
+style guideline and have the following two exceptions. New scripts should,
+however, be PEP-8 compliant.
 
   * Use two-space indentation instead of four-space indentation.
   * Use `CamelCase()` method and function names instead of `unix_hacker_style()` names.
 
-(The rationale for these is mostly legacy: the code was originally written
-following Google's internal style guideline, the cost of updating all of the
-code to PEP-8 compliance was not small, and consistency was seen to be a
-greater virtue than compliance.)
-
 [Depot tools](http://commondatastorage.googleapis.com/chrome-infra-docs/flat/depot_tools/docs/html/depot_tools.html)
 contains a local copy of pylint, appropriately configured.