Fix 'git cl format'

git_cl.py

Index: git_cl.py
diff --git a/git_cl.py b/git_cl.py
index b34edcf38df385ee4be9566372e16259c696c6d4..6d85ca5b92b7a61619a501b6e896f468252a42d9 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -1952,24 +1952,35 @@ def CMDformat(parser, args):
   if args:
     parser.error('Unrecognized args: %s' % ' '.join(args))
 
+  # Generate diff for the current branch's changes.
+  diff_cmd = ['diff', '--no-ext-diff']
   if opts.full:
-    cmd = ['diff', '--name-only', '--'] + ['.*' + ext for ext in CLANG_EXTS]
-    files = RunGit(cmd).split()
+    # Only list the names of modified files.
+    diff_cmd += ['--name-only']

[M-A Ruel, 2013/05/17 12:41:48]

I highly prefer append() even if it is clunky. It's because it's just too easy
to get the wrong result otherwise.

+  else:
+    # Only generate context-less patches.
+    diff_cmd += ['-U0']
+
+  # Handle branch and source file filtering.
+  diff_cmd += ['@{u}', '--'] + ['*' + ext for ext in CLANG_EXTS]

[M-A Ruel, 2013/05/17 12:41:48]

Note that @{u} may not be exactly what you want. I recommend you to use the
cl.GetUpstreamBranch() function like used elsewhere.

Also, even that may not get the right diff. For example, the user may have
called git fetch origin but hadn't rebased yet. 
So you want to use the merge-base commit, e.g.

git merge-base HEAD cl.GetUpstreamBranch()

I understand you are simply moving code around but the previous code was wrong.

+  diff_output = RunGit(diff_cmd)
+
+  if opts.full:
+    # diff_output is a list of files to send to clang-format.
+    files = diff_output.split()
     if not files:
       print "Nothing to format."
       return 0
-    RunCommand(['clang-format', '-i'] + files)
+    RunCommand(['clang-format', '-i', '-style', 'Chromium'] + files)
   else:
+    # diff_output is a patch to send to clang-format-diff.py
     cfd_path = os.path.join('/usr', 'lib', 'clang-format',
                             'clang-format-diff.py')
     if not os.path.exists(cfd_path):
       print >> sys.stderr, 'Could not find clang-format-diff at %s.' % cfd_path
       return 2
-    cmd = ['diff', '-U0', '@{u}', '--'] + ['.*' + ext for ext in CLANG_EXTS]
-    diff = RunGit(cmd)
-    cmd = [sys.executable, '/usr/lib/clang-format/clang-format-diff.py',
-           '-style', 'Chromium']
-    RunCommand(cmd, stdin=diff)
+    cmd = [sys.executable, cfd_path, '-style', 'Chromium']
+    RunCommand(cmd, stdin=diff_output)
 
   return 0