Devserver: allow SubversionFileSystem to be pinned to a specific rev on construction

chrome/common/extensions/docs/server2/appengine_wrappers.py

Index: chrome/common/extensions/docs/server2/appengine_wrappers.py
diff --git a/chrome/common/extensions/docs/server2/appengine_wrappers.py b/chrome/common/extensions/docs/server2/appengine_wrappers.py
index 745ec35fbee58b1ffc10a6b0fd021d62e291bb6e..86a43e4940fc6268f32b6b3ffd8f8d476a45eb29 100644
--- a/chrome/common/extensions/docs/server2/appengine_wrappers.py
+++ b/chrome/common/extensions/docs/server2/appengine_wrappers.py
@@ -4,19 +4,16 @@
 
 import os
 
+from app_yaml_helper import AppYamlHelper
+
 def GetAppVersion():
   if 'CURRENT_VERSION_ID' in os.environ:
     # The version ID looks like 2-0-25.36712548, we only want the 2-0-25.
     return os.environ['CURRENT_VERSION_ID'].split('.', 1)[0]
-  # Not running on appengine, get it from the app.yaml file ourselves. We
-  # could properly parse this using a yaml library but Python doesn't have
-  # one built in so whatevs.
-  version_key = 'version:'
+  # Not running on appengine, get it from the app.yaml file ourselves.
   app_yaml_path = os.path.join(os.path.split(__file__)[0], 'app.yaml')
   with open(app_yaml_path, 'r') as app_yaml:
-    version_line = [line for line in app_yaml.read().split('\n')
-                    if line.startswith(version_key)][0]
-  return version_line[len(version_key):].strip()
+    return AppYamlHelper.ExtractVersion(app_yaml.read())
 
 def IsDevServer():
   return os.environ.get('SERVER_SOFTWARE', '').find('Development') == 0