Fix pylint presubmit check so that it works on Windows.

presubmit_canned_checks.py

Index: presubmit_canned_checks.py
diff --git a/presubmit_canned_checks.py b/presubmit_canned_checks.py
index 90c79ccfcc6deda18a16bed8dfdc65d4848579e4..117167d6ec51688631c55b901d24fe459429c904 100644
--- a/presubmit_canned_checks.py
+++ b/presubmit_canned_checks.py
@@ -643,9 +643,16 @@ def RunPylint(input_api, output_api, white_list=None, black_list=None,
   # Only trigger if there is at least one python file affected.
   def rel_path(regex):
     """Modifies a regex for a subject to accept paths relative to root."""
-    if input_api.os_path.samefile(
-        input_api.PresubmitLocalPath(), input_api.change.RepositoryRoot()):
-      return regex
+    if hasattr(input_api.os_path, 'samefile'):

[M-A Ruel, 2013/01/18 16:31:46]

Actually, it could be written shorter with:

def samefile(a, b):
  # Default implementation for platforms lacking os.path.samefile like Windows.
  return input_api.os_path.abspath(a) == input_api.os_path.abspath(b)

samefile = getattr(input_api.os_path, 'samefile', samefile)
if samefile(input_api.PresubmitLocalPath(), input_api.change.RepositoryRoot()):
  return regex

[chrisha, 2013/01/18 16:52:12]

And this is where it shows that I'm not really a Python guy ;)

Done.

+      if input_api.os_path.samefile(input_api.PresubmitLocalPath(),
+                                    input_api.change.RepositoryRoot()):
+        return regex
+    else:
+      # 'samefile' doesn't exist on Windows, so we fall back to an exact
+      # path match.
+      if (input_api.os_path.abspath(input_api.PresubmitLocalPath()) ==
+          input_api.os_path.abspath(input_api.change.RepositoryRoot())):
+        return regex
     prefix = input_api.os_path.join(input_api.os_path.relpath(
         input_api.PresubmitLocalPath(), input_api.change.RepositoryRoot()), '')
     return input_api.re.escape(prefix) + regex