Make tools/run_hooks.py work when depot_tools is not in PATH

tools/run_hooks.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.
 
 # This script runs all of the hooks specified in DEPS in order.
 
 import os
 import subprocess
 import sys
 
 scope = {}
 
 def Var(key):
   return scope["vars"][key]
 
 scope["Var"] = Var
 
 def main(args):
   gclient_path = os.path.abspath(os.path.join(os.path.dirname(__file__),
     os.pardir, os.pardir))
   deps_path = os.path.join(gclient_path, "src", "DEPS")
   with open(deps_path) as deps_contents:
     d = deps_contents.read()
   exec(d, scope)
+  env = os.environ
+  # Some hooks expect depot_tools to be in the PATH already. If there is no
+  # depot_tools in the current environment's PATH add the default location of
+  # depot_tools in a standard checkout to the environment the hooks run in.
+  if env["PATH"].find("depot_tools") == -1:

[lanechr, 2016/03/04 17:35:41]

why not just add the default_depot_tools_path to the end of the PATH?  it would
better handle the case of the user having a depot_tools directory that doesn't
include the tool you want.  plus, this is kind of what PATH does.

+    default_depot_tools_path = os.path.join(gclient_path, "depot_tools")
+    env["PATH"] = env["PATH"] + ":" + default_depot_tools_path
   for hook in scope["hooks"]:
     name = hook["name"]
     print "________ running '%s' in '%s'" % (" ".join(hook["action"]),
         gclient_path)
-    subprocess.check_call(hook["action"], cwd=gclient_path)
+    subprocess.check_call(hook["action"], cwd=gclient_path, env=env)
     print
   return 0
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))