CrOS: Load Chromite pins from JSON.

scripts/common/env.py

 #!/usr/bin/env python
 # Copyright 2015 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.
 
 """Implements a standard mechanism for Chrome Infra Python environment setup.
 
 This library provides a central location to define Chrome Infra environment
 setup. It also provides several faculties to install this environment.
 
@@ skipping 28 matching lines @@
 import traceback
 
 
 # Export for bootstrapping.
 __all__ = [
     'Install',
     'PythonPath',
     ]
 
 
+# This is the path of the current "env" module. When "env" is run from
+# command-line, this path is automatically appended, and should be stripped out
+# of system path generation.
+_env_module_path = os.path.abspath(os.path.dirname(__file__))
+
 # Name of enviornment extension file to seek.
 ENV_EXTENSION_NAME = 'environment.cfg.py'
 
 # Standard directories (based on this file's location in the <build> tree).
 def path_if(*args):
   if not all(args):
     return None
   path = os.path.abspath(os.path.join(*args))
   return (path) if os.path.exists(path) else (None)
 
@@ skipping 244 matching lines @@
       sys.path = orig_sys_path
       SetPythonPathEnv(orig_pythonpath)
 
 
 def GetSysPythonPath(hermetic=True):
   """Returns (PythonPath): A path based on 'sys.path'.
 
   Args:
     hermetic (bool): If True, prune any non-system path.
   """
-  path = PythonPath.FromPaths(*sys.path)
+  sys_paths = [p for p in sys.path
+               if p != _env_module_path]
+  path = PythonPath.FromPaths(*sys_paths)
   if hermetic:
     path = path.GetHermetic()
   return path
 
 
 def GetEnvPythonPath():
   """Returns (PythonPath): A path based on the PYTHONPATH environment variable.
   """
   pythonpath = os.environ.get('PYTHONPATH')
   if not pythonpath:
@@ skipping 106 matching lines @@
   # Parse
   args = parser.parse_args()
 
   # Execute our subcommand function, which will return the exit code.
   path = _InfraPathFromArgs(args)
   return args.func(args, path)
 
 
 if __name__ == '__main__':
   sys.exit(main())