bot_update: fix git dir check

recipe_modules/bot_update/resources/bot_update.py

 #!/usr/bin/env python
 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # TODO(hinoka): Use logging.
 
 import cStringIO
 import codecs
 import collections
@@ skipping 810 matching lines @@
       'status', '--porcelain', deps_file, cwd=repo_base).strip()
   if deps_file_status and deps_file_status.startswith('M '):
     return True
 
   last_known_deps_ref = _last_commit_for_file(deps_file, repo_base)
   last_known_deps_git_ref = _last_commit_for_file(deps_git_file, repo_base)
   merge_base_ref = git('merge-base', last_known_deps_ref,
                        last_known_deps_git_ref, cwd=repo_base).strip()
 
   # If the merge base of the last DEPS and last .DEPS.git file is not
-  # equivilent to the hash of the last DEPS file, that means the DEPS file
+  # equivalent to the hash of the last DEPS file, that means the DEPS file
   # was committed after the last .DEPS.git file.
   return last_known_deps_ref != merge_base_ref
 
 
 def ensure_deps2git(solution, shallow, git_cache_dir):
   repo_base = path.join(os.getcwd(), solution['name'])
   deps_file = path.join(repo_base, 'DEPS')
   deps_git_file = path.join(repo_base, '.DEPS.git')
   if (not git('ls-files', 'DEPS', cwd=repo_base).strip() or
       not git('ls-files', '.DEPS.git', cwd=repo_base).strip()):
@@ skipping 111 matching lines @@
       for ref in refs:
         populate_cmd.extend(['--ref', ref])
       git(*populate_cmd)
       mirror_dir = git(
           'cache', 'exists', '--quiet',
           '--cache-dir', git_cache_dir, url).strip()
       clone_cmd = (
           'clone', '--no-checkout', '--local', '--shared', mirror_dir, sln_dir)
 
       try:
-        if not path.isdir(sln_dir):
+        if not path.isdir(os.path.join(sln_dir, '.git')):
           git(*clone_cmd)
         else:
           git('remote', 'set-url', 'origin', mirror_dir, cwd=sln_dir)
           git('fetch', 'origin', cwd=sln_dir)
         for ref in refs:
           refspec = '%s:%s' % (ref, ref.lstrip('+'))
           git('fetch', 'origin', refspec, cwd=sln_dir)
 
         revision = get_target_revision(name, url, revisions) or 'HEAD'
         force_revision(sln_dir, revision)
@@ skipping 794 matching lines @@
   except Exception:
     # Unexpected failure.
     emit_flag(options.flag_file)
     raise
   else:
     emit_flag(options.flag_file)
 
 
 if __name__ == '__main__':
   sys.exit(main())