The last change to create_sdk.py failed if the 'sdk' dir already existed

tools/create_sdk.py

 #!/usr/bin/env python
 #
 # Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 #
 # A script which will be invoked from gyp to create an SDK. The SDK will be
 # used either from the command-line or from the editor. Top structure is
 # 
 # ..sdk/
@@ skipping 63 matching lines @@
     (eval(open("frog/lib/frog_json_sources.gypi").read()))['sources']
 
   HOME = dirname(dirname(realpath(__file__)))
 
   SDK = argv[1]
 
   # TODO(dgrove) - deal with architectures that are not ia32.
   if (os.path.basename(os.path.dirname(SDK)) != 
       utils.GetBuildConf('release', 'ia32')):
     print "SDK is not built in Debug mode."
-    # leave empty dir behind
-    os.makedirs(SDK)
+    if not os.path.exists(SDK):
+      # leave empty dir behind
+      os.makedirs(SDK)
     exit(0)
 
   if exists(SDK):
     rmtree(SDK)
 
   # Create and populate sdk/bin.
   BIN = join(SDK, 'bin')
   os.makedirs(BIN)
 
   # Copy the Dart VM binary into sdk/bin.
@@ skipping 255 matching lines @@
   # Create and copy tools.
 
   UTIL = join(SDK, 'tools')
   os.makedirs(UTIL)
 
   copytree(join(HOME, 'utils', 'dartdoc'), join(UTIL, 'dartdoc'), 
            ignore=ignore_patterns('.svn'))
 
 if __name__ == '__main__':
   sys.exit(Main(sys.argv))