Add debug logging to debug why...

Add debug logging to debug why https://chromium-review.googlesource.com/c/1346670 has no effect on the bot.

TBR=hans@chromium.org

Bug: 899438
Change-Id: Ibec766f0ccf5554556c4c578625469d20504fff9
Reviewed-on: https://chromium-review.googlesource.com/c/1347211Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610178}

tools/determinism/compare_build_artifacts.py

@@ -190,7 +190,12 @@ def compare_files(first_filepath, second_filepath):
     with open(second_filepath, 'rb') as f:
       lhs_cwd = lhs['relative_cwd']
       rhs_cwd = rhs['relative_cwd']
-      rhs = json.loads(f.read().replace(rhs_cwd, lhs_cwd))
+      json_contents = f.read()
+      print >>sys.stderr, 'raw contents', second_filepath, ':', json_contents
+      json_contents = json_contents.replace(rhs_cwd, lhs_cwd)
+      print >>sys.stderr, 'transformed', rhs_cwd, lhs_cwd, json_contents
+      rhs = json.loads(json_contents)
+      print >>sys.stderr, 'objects', lhs, rhs
     diff = diff_dict(lhs, rhs)
     if diff:
       return '\n' + '\n'.join('  ' + line for line in diff.splitlines())