Add more temporary debugging output to PRESUBMIT.py

PRESUBMIT.py

Index: PRESUBMIT.py
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 5eee2ba31ceb17b5c0576109110901f98274785b..71907be309d23404e3a5b8dbda6bd682cd2febc5 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -61,10 +61,12 @@ def _CommonChecks(input_api, output_api):
 def _SkipTreeCheck(input_api, output_api):
   """Check the env var whether we want to skip tree check.
      Only skip if src/version.cc has been updated."""
+  print "skip tree check?", input_api.environ.get('PRESUBMIT_TREE_CHECK')
   src_version = 'src/version.cc'
-  FilterFile = lambda file: file.LocalPath() == src_version
-  if not input_api.AffectedSourceFiles(
-      lambda file: file.LocalPath() == src_version):
+  def FilterFile(file):
+    print "Changed file:", file.LocalPath()
+    return file.LocalPath() == src_version
+  if not input_api.AffectedSourceFiles(FilterFile):
     return False
   if input_api.environ.get('PRESUBMIT_TREE_CHECK') == 'skip':
     print "Skip tree check requested via environment variable."