Make building from bleeding edge tarball possible without Subversion installed

tools/utils.py

 # Copyright (c) 2012, 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.
 
 # This file contains a set of utilities functions used by other Python-based
 # scripts.
 
 import commands
 import os
 import platform
@@ skipping 300 matching lines @@
   prerelease_patch = match_against('^PRERELEASE_PATCH (\d+)$', content)
 
   if channel and major and minor and prerelease and prerelease_patch:
     return Version(
         channel, major, minor, patch, prerelease, prerelease_patch)
   else:
     print "Warning: VERSION file (%s) has wrong format" % version_file
     return None
 
 def GetSVNRevision():
+  # When building from tarball use tools/SVN_REVISION
+  svn_revision_file = os.path.join(DART_DIR, 'tools', 'SVN_REVISION')
+  try:
+    with open(svn_revision_file) as fd:
+      return fd.read()
+  except:
+    pass
+
   # FIXME(kustermann): Make this work for newer SVN versions as well (where
   # we've got only one '.svn' directory)
   custom_env = dict(os.environ)
   custom_env['LC_MESSAGES'] = 'en_GB'
   p = subprocess.Popen(['svn', 'info'], stdout = subprocess.PIPE,
                        stderr = subprocess.STDOUT, shell=IsWindows(),
                        env = custom_env,
                        cwd = DART_DIR)
   output, _ = p.communicate()
   revision = ParseSvnInfoOutput(output)
   if revision:
     return revision
 
   # maybe the builder is using git-svn, try that
   p = subprocess.Popen(['git', 'svn', 'info'], stdout = subprocess.PIPE,
       stderr = subprocess.STDOUT, shell=IsWindows(), cwd = DART_DIR)
   output, _ = p.communicate()
   revision = ParseSvnInfoOutput(output)
   if revision:
     return revision
 
-  # When building from tarball use tools/SVN_REVISION
-  svn_revision_file = os.path.join(DART_DIR, 'tools', 'SVN_REVISION')
-  try:
-    with open(svn_revision_file) as fd:
-      return fd.read()
-  except:
-    pass
-
   # Only fail on the buildbot in case of a SVN client version mismatch.
   user = GetUserName()
   if user != 'chrome-bot':
     return '0'
 
   return None
 
 def ParseSvnInfoOutput(output):
   revision_match = re.search('Last Changed Rev: (\d+)', output)
   if revision_match:
@@ skipping 174 matching lines @@
     os.chdir(self._working_directory)
 
   def __exit__(self, *_):
     print "Enter directory = ", self._old_cwd
     os.chdir(self._old_cwd)
 
 
 if __name__ == "__main__":
   import sys
   Main(sys.argv)