Revert "run some tests using python3"

This reverts commit 658f361a34e21b92902a6b4c74047363b053cad3.

Reason for revert: crbug.com/1274039 (breaks ASAN bots)

Original change's description:
> run some tests using python3
>
> Bug: 941669
> Change-Id: Ib63daab2a4cb3868cfc37121c3f48ebb2019af39
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3301620
> Auto-Submit: Takuto Ikuta <tikuta@chromium.org>
> Commit-Queue: Nico Weber <thakis@chromium.org>
> Reviewed-by: Nico Weber <thakis@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#945345}

Bug: 941669, 1274039
Change-Id: Ib271b4e80ca4969f871eb1bc341a81449783a014
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3302106
Commit-Queue: Alexander Hendrich <hendrich@chromium.org>
Owners-Override: Alexander Hendrich <hendrich@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#945573}
NOKEYCHECK=True
GitOrigin-RevId: 17304dfd2f915f3f98d7b1d43b230e860f4ffdd9
diff --git a/asan/asan_symbolize.py b/asan/asan_symbolize.py
index a9d0ba0..0d1c880 100755
--- a/asan/asan_symbolize.py
+++ b/asan/asan_symbolize.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
@@ -180,8 +180,7 @@
     return '\n'.join(symbolized_lines)
 
   def symbolize(self, test_run):
-    original_snippet = base64.b64decode(
-        test_run['output_snippet_base64']).decode('utf-8', 'replace')
+    original_snippet = base64.b64decode(test_run['output_snippet_base64'])
     symbolized_snippet = self.symbolize_snippet(original_snippet)
     if symbolized_snippet == original_snippet:
       # No sanitizer reports in snippet.
@@ -191,9 +190,9 @@
     test_run['original_output_snippet_base64'] = \
         test_run['output_snippet_base64']
 
-    test_run['output_snippet'] = symbolized_snippet
+    test_run['output_snippet'] = symbolized_snippet.decode('utf-8', 'replace')
     test_run['output_snippet_base64'] = \
-        base64.b64encode(symbolized_snippet.encode('utf-8', 'replace')).decode()
+        base64.b64encode(symbolized_snippet)
     test_run['snippet_processed_by'] = 'asan_symbolize.py'
 
 
@@ -203,7 +202,7 @@
 
   test_run_symbolizer = JSONTestRunSymbolizer(symbolization_loop)
   for iteration_data in json_data['per_iteration_data']:
-    for test_name, test_runs in iteration_data.items():
+    for test_name, test_runs in iteration_data.iteritems():
       for test_run in test_runs:
         test_run_symbolizer.symbolize(test_run)