Revert "[git_bootstrap.py] Remove unused options, use cipd in %PATH%."

This reverts commit 1123fea235.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> [git_bootstrap.py] Remove unused options, use cipd in %PATH%.
> 
> In particular:
>   * Rely on cipd.bat in %PATH%
>   * Always calculate --bits
>   * Rely on %CIPD_CACHE_DIR%
> 
> R=​vadimsh@chromium.org
> 
> Bug: 635421
> Change-Id: I972edfd7f48e90770696afba70ec7e11fc24ce95
> Reviewed-on: https://chromium-review.googlesource.com/495407
> Commit-Queue: Robbie Iannucci <iannucci@chromium.org>
> Reviewed-by: Vadim Shtayura <vadimsh@chromium.org>
> 

TBR=iannucci@chromium.org,vadimsh@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: I3536d6668432141ae1528ca49ea66d97fdeb5318
Reviewed-on: https://chromium-review.googlesource.com/495727
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Robbie Iannucci <iannucci@chromium.org>

bootstrap/win/git_bootstrap.py

@@ -27,6 +27,11 @@ def _check_call(argv, **kwargs):
   subprocess.check_call(argv, **kwargs)
 
 
+def get_os_bitness():
+  """Returns bitness of operating system as int."""
+  return 64 if platform.machine().endswith('64') else 32
+
+
 def get_target_git_version():
   """Returns git version that should be installed."""
   if os.path.exists(os.path.join(ROOT_DIR, '.git_bleeding_edge')):
@@ -48,18 +53,24 @@ def clean_up_old_git_installations(git_directory):
 
 def cipd_install(args, dest_directory, package, version):
   """Installs CIPD |package| at |version| into |dest_directory|."""
+  manifest_file = tempfile.mktemp()
+  try:
+    with open(manifest_file, 'w') as f:
+      f.write('%s %s\n' % (package, version))
+
     cipd_args = [
-    'cipd.bat',
+      args.cipd_client,
       'ensure',
-    '-ensure-file', '-',
+      '-list', manifest_file,
       '-root', dest_directory,
     ]
+    if args.cipd_cache_directory:
+      cipd_args.extend(['-cache-dir', args.cipd_cache_directory])
     if args.verbose:
       cipd_args.append('-verbose')
-  p = subprocess.Popen(cipd_args, stdin=subprocess.PIPE)
-  p.communicate('%s %s\n' % (package, version))
-  if p.wait() != 0:
-    raise subprocess.CalledProcessError(p.returncode, cipd_args)
+    _check_call(cipd_args)
+  finally:
+    os.remove(manifest_file)
 
 
 def need_to_install_git(args, git_directory):
@@ -87,9 +98,9 @@ def need_to_install_git(args, git_directory):
   return False
 
 
-def install_git(args, bits, git_version, git_directory):
+def install_git(args, git_version, git_directory):
   """Installs |git_version| into |git_directory|."""
-  cipd_platform = 'windows-%s' % ('amd64' if bits == 64 else '386')
+  cipd_platform = 'windows-%s' % ('amd64' if args.bits == 64 else '386')
   temp_dir = tempfile.mkdtemp()
   try:
     cipd_install(args,
@@ -143,6 +154,14 @@ def install_git(args, bits, git_version, git_directory):
 
 def main(argv):
   parser = argparse.ArgumentParser()
+  parser.add_argument('--bits', type=int, choices=(32,64),
+                      help='Bitness of the client to install. Default on this'
+                      ' system: %(default)s', default=get_os_bitness())
+  parser.add_argument('--cipd-client',
+                      help='Path to CIPD client binary. default: %(default)s',
+                      default=os.path.join(ROOT_DIR, 'cipd'+BAT_EXT))
+  parser.add_argument('--cipd-cache-directory',
+                      help='Path to CIPD cache directory.')
   parser.add_argument('--force', action='store_true',
                       help='Always re-install git.')
   parser.add_argument('--verbose', action='store_true')
@@ -153,18 +172,16 @@ def main(argv):
 
   logging.basicConfig(level=logging.INFO if args.verbose else logging.WARN)
 
-  bits = 64 if platform.machine().endswith('64') else 32
-
   git_version = get_target_git_version()
   git_directory = os.path.join(
-      ROOT_DIR, 'git-%s-%s_bin' % (git_version, bits))
+      ROOT_DIR, 'git-%s-%s_bin' % (git_version, args.bits))
   git_docs_dir = os.path.join(
-      git_directory, 'mingw%s' % bits, 'share', 'doc', 'git-doc')
+      git_directory, 'mingw%s' % args.bits, 'share', 'doc', 'git-doc')
 
   clean_up_old_git_installations(git_directory)
 
   if need_to_install_git(args, git_directory):
-    install_git(args, bits, git_version, git_directory)
+    install_git(args, git_version, git_directory)
 
   # Update depot_tools files for "git help <command>"
   docsrc = os.path.join(ROOT_DIR, 'man', 'html')