Check the existence and executability of scm commands

gclient_utils.py

Index: gclient_utils.py
===================================================================
--- gclient_utils.py	(revision 132376)
+++ gclient_utils.py	(working copy)
@@ -193,6 +193,16 @@
         raise
 
 
+def FindCommandExecutable(cmd):
+  """Finds the specified |cmd| in $PATH and returns its path.  Returns None
+  if it's not found."""
+  for path in os.environ['PATH'].split(os.pathsep):
+    full_path = os.path.join(path, cmd)
+    if os.path.isfile(full_path) and os.access(full_path, os.X_OK):
+      return full_path
+  return None
+
+
 def CheckCallAndFilterAndHeader(args, always=False, **kwargs):
   """Adds 'header' support to CheckCallAndFilter.