rebaseline.py: error out early if --expectations-root not pointing at gm-expected dir

tools/rebaseline.py

 #!/usr/bin/python
 
 '''
 Copyright 2012 Google Inc.
 
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 '''
 
 '''
@@ skipping 170 matching lines @@
                         skipped_images.append(image_name)
                         continue
                 expectations_dict[gm_json.JSONKEY_EXPECTEDRESULTS] \
                                  [image_name] \
                                  [gm_json.JSONKEY_EXPECTEDRESULTS_ALLOWEDDIGESTS] = \
                                      [image_results]
 
         # Write out updated expectations.
         gm_json.WriteToFile(expectations_dict, expectations_json_filepath)
 
-        if skipped_images:
-            print ('Skipped these tests due to test/config filters: %s' %
-                   skipped_images)
-
 
 # main...
 
 parser = argparse.ArgumentParser()
 parser.add_argument('--actuals-base-url',
                     help='base URL from which to read files containing JSON ' +
                     'summaries of actual GM results; defaults to %(default)s',
                     default='http://skia-autogen.googlecode.com/svn/gm-actual')
 parser.add_argument('--actuals-filename',
                     help='filename (within platform-specific subdirectories ' +
@@ skipping 63 matching lines @@
                                           args.expectations_filename)
     if os.path.isfile(expectations_json_file):
         rebaseliner = JsonRebaseliner(
             expectations_root=args.expectations_root,
             expectations_filename=args.expectations_filename,
             tests=args.tests, configs=args.configs,
             actuals_base_url=args.actuals_base_url,
             actuals_filename=args.actuals_filename,
             add_new=args.add_new)
     else:
+        # TODO(epoger): When we get rid of the ImageRebaseliner implementation,
+        # we should raise an Exception in this case (no JSON expectations file
+        # found to update), to prevent a recurrence of
+        # https://code.google.com/p/skia/issues/detail?id=1403 ('rebaseline.py
+        # script fails with misleading output when run outside of gm-expected
+        # dir')
         rebaseliner = rebaseline_imagefiles.ImageRebaseliner(
             expectations_root=args.expectations_root,
             tests=args.tests, configs=args.configs,
             dry_run=args.dry_run,
             json_base_url=args.actuals_base_url,
             json_filename=args.actuals_filename,
             add_new=args.add_new,
             missing_json_is_fatal=missing_json_is_fatal)
     rebaseliner.RebaselineSubdir(subdir=subdir, builder=builder)