Fix a bug in Warn(), simplify code

gcl.py

Index: gcl.py
diff --git a/gcl.py b/gcl.py
index 55144ccf45076224a75239c829c9c20b9be580b1..e8532e12d8be914a6383f25e3e5f75fb8e7a97b6 100755
--- a/gcl.py
+++ b/gcl.py
@@ -184,14 +184,12 @@ def GetCodeReviewSetting(key):
 
 
 def Warn(msg):
-  ErrorExit(msg, exit=False)
+  print >> sys.stderr, msg
 
 
-def ErrorExit(msg, do_exit=True):
-  """Print an error message to stderr and optionally exit."""
+def ErrorExit(msg):
   print >> sys.stderr, msg
-  if do_exit:
-    sys.exit(1)
+  sys.exit(1)
 
 
 def RunShellWithReturnCode(command, print_output=False):