Fix prompt exporting escaped characters, opt into PS1 mod.

go/bootstrap.py

 #!/usr/bin/env python
 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Prepares a local hermetic Go installation.
 
 - Downloads and unpacks the Go toolset in ../../golang.
 - Downloads and installs Glide (used by deps.py).
 - Fetches code dependencies via deps.py.
@@ skipping 376 matching lines @@
   # APPENGINE_DEV_APPSERVER is used by "appengine/aetest" package. If it's
   # missing, aetest will scan PATH looking for dev_appserver.py, possibly
   # finding it in some other place.
   if go_appengine_path:
     env['APPENGINE_DEV_APPSERVER'] = os.path.join(
         go_appengine_path, 'dev_appserver.py')
   else:
     env.pop('APPENGINE_DEV_APPSERVER', None)
 
   # Add a tag to the prompt
-  prompt = env.get('PS1')
-  if prompt:
-    prompttag = env.get('INFRA_PROMPT_TAG', '[cr go] ')
-    if prompttag not in prompt:
-      env['PS1'] = prompttag + prompt
+  infra_prompt_tag = env.get('INFRA_PROMPT_TAG')
+  if infra_prompt_tag is None:
+    infra_prompt_tag = '[cr go] '
+  if infra_prompt_tag:
+    prompt = env.get('PS1')
+    if prompt and infra_prompt_tag not in prompt:
+      env['PS1'] = infra_prompt_tag + prompt
 
   return env
 
 
 def get_go_exe(toolset_root):
   """Returns path to go executable."""
   return os.path.join(toolset_root, 'go', 'bin', 'go' + EXE_SFX)
 
 
 def bootstrap(go_paths, logging_level):
@@ skipping 66 matching lines @@
   return name
 
 
 def main():
   bootstrap([WORKSPACE], logging.DEBUG)
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())