Observatory build should try backup method if the SDK doesn't work.

tools/run_pub.py

-#!/usr/bin/env python
-# Copyright (c) 2015, 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.
-"""Used to run pub before the SDK has been built"""
-
-import argparse
-import os
-import platform
-import subprocess
-import sys
-
-SCRIPT_DIR = os.path.dirname(sys.argv[0])
-DART_ROOT = os.path.realpath(os.path.join(SCRIPT_DIR, '..'))
-PUB_PATH = os.path.join(DART_ROOT, 'third_party/pkg/pub/bin/pub.dart')
-CANARY_PATH = os.path.join(DART_ROOT, 'tools', 'canary.dart')
-
-usage = """run_pub.py --package-root=<package root>"""
-
-def BuildArguments():
-  result = argparse.ArgumentParser(usage=usage)
-  result.add_argument("--package-root", help="package root", default=None)
-  result.add_argument("--dart-executable", help="dart binary", default=None)
-  return result
-
-def ProcessOptions(options, args):
-  return ((options.package_root != None) and
-          (options.dart_executable != None))
-
-def GetPrebuiltDartExecutablePath(suffix):
-  osdict = {'Darwin':'macos', 'Linux':'linux', 'Windows':'windows'}
-  system = platform.system()
-  executable_name = 'dart'
-  if system == 'Windows':
-    executable_name = 'dart.exe'
-  try:
-    osname = osdict[system]
-  except KeyError:
-    print >>sys.stderr, ('WARNING: platform "%s" not supported') % (system)
-    return None;
-  return os.path.join(DART_ROOT,
-                      'tools',
-                      'testing',
-                      'bin',
-                      osname,
-                      executable_name + suffix)
-
-def RunPub(dart, pkg_root, args):
-  return subprocess.call([dart, '--package-root=' + pkg_root, PUB_PATH] + args)
-
-def TryRunningExecutable(dart_executable, pkg_root):
-  try:
-    return subprocess.call([dart_executable,
-                            '--package-root=' + pkg_root,
-                            CANARY_PATH]) == 42
-  except:
-    return False;
-
-def DisplayBootstrapWarning():
-  print """\
-
-
-WARNING: Your system cannot run the prebuilt Dart executable. Using the
-bootstrap Dart executable will make Debug builds long.
-Please see Wiki for instructions on replacing prebuilt Dart executable.
-
-https://code.google.com/p/dart/wiki/ReplacingPrebuiltDartExecutable
-
-"""
-
-def FindDartExecutable(fallback_executable, package_root):
-  # If requested, use the bootstrap binary instead of the prebuilt
-  # executable.
-  if os.getenv('DART_USE_BOOTSTRAP_BIN') != None:
-    return fallback_executable
-  # Try to find a working prebuilt dart executable.
-  dart_executable = GetPrebuiltDartExecutablePath('')
-  if TryRunningExecutable(dart_executable, package_root):
-    return dart_executable
-  dart_executable = GetPrebuiltDartExecutablePath('-arm')
-  if TryRunningExecutable(dart_executable, package_root):
-    return dart_executable
-  dart_executable = GetPrebuiltDartExecutablePath('-mips')
-  if TryRunningExecutable(dart_executable, package_root):
-    return dart_executable
-  # If the system cannot execute a prebuilt dart executable, use the bootstrap
-  # executable instead.
-  DisplayBootstrapWarning()
-  return fallback_executable
-
-def main():
-  # Parse the options.
-  parser = BuildArguments()
-  (options, args) = parser.parse_known_args()
-  if not ProcessOptions(options, args):
-    parser.print_help()
-    return 1
-  dart_executable = FindDartExecutable(options.dart_executable,
-                                       options.package_root)
-  return RunPub(dart_executable, options.package_root, args)
-
-
-if __name__ == '__main__':
-  sys.exit(main())