Remove code duplication and improve style.

gcl.py

Index: gcl.py
diff --git a/gcl.py b/gcl.py
index 24d410907b4972380e749ddb21b35400e4cbe5bc..62f1b94e01c9a8a1dcc27da44cec8a74480f48e4 100755
--- a/gcl.py
+++ b/gcl.py
@@ -204,14 +204,8 @@ def ErrorExit(msg):
 
 def RunShellWithReturnCode(command, print_output=False):
   """Executes a command and returns the output and the return code."""
-  # Use a shell for subcommands on Windows to get a PATH search, and because svn
-  # may be a batch file.
-  use_shell = sys.platform.startswith("win")
-  env = os.environ.copy()
-  env['LANGUAGE'] = 'en'
-  p = subprocess.Popen(command, stdout=subprocess.PIPE,
-                       stderr=subprocess.STDOUT, shell=use_shell, env=env,
-                       universal_newlines=True)
+  p = gclient_utils.Popen(command, stdout=subprocess.PIPE,
+                          stderr=subprocess.STDOUT, universal_newlines=True)
   if print_output:
     output_array = []
     while True: