Replace OSError by the correct class IOError

R=dpranke@chromium.org
BUG=
TEST=

Review URL: http://codereview.chromium.org/7215025

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@89884 0039d316-1c4b-4281-b951-d872f2087c98

checkout.py

@@ -42,7 +42,7 @@ def get_code_review_setting(path, key,
         settings[k.strip()] = v.strip()
     finally:
       settings_file.close()
-  except OSError:
+  except IOError:
     return None
   return settings.get(key, None)