checkout: have my cake and eat it too

Turns out that checkout-index can acutally be passed multiple paths
(like most git commands).  This should give the same performance
increase as before but without needing an extra argument and including
the benefit for everyone else.

Thanks @demonyangyue!

git_fat/git_fat.py

@@ -839,43 +839,21 @@ def _remove_orphan_file(self, fname):
         if recheck_digest:
             delete_file(fname)
 
-    def checkout_all_index(self, show_orphans=False, **unused_kwargs):
-        '''
-        Checkout all files from index when restoring many binaries, to enhance the performance.
-        Need the working directory to be clean.
-        '''
-        # avoid unstaged changed being overwritten
-        if sub.check_output(["git", "ls-files", "-m"]):
-            print('You have unstaged changes in working directory')
-            print('please use "git add <file>..." to stage those changes'
-                  ' or use "git checkout -- <file>..." to discard changes')
-            exit(1)
-
-        for digest, fname in self._orphan_files():
-            objpath = os.path.join(self.objdir, digest)
-            if os.access(objpath, os.R_OK):
-                print('Will restore %s -> %s' % (digest, fname))
-                self._remove_orphan_file(fname)
-            elif show_orphans:
-                print('Data unavailable: %s %s' % (digest, fname))
-
-        print('Restoring files ...')
-        # This re-smudge is essentially a copy that restores permissions.
-        sub.check_call(['git', 'checkout-index', '--index', '--force', '--all'])
-
     def checkout(self, show_orphans=False, **unused_kwargs):
         '''
         Update any stale files in the present working tree
         '''
+        to_checkout = []
         for digest, fname in self._orphan_files():
             objpath = os.path.join(self.objdir, digest)
             if os.access(objpath, os.R_OK):
                 print('Restoring %s -> %s' % (digest, fname))
                 self._remove_orphan_file(fname)
                 # This re-smudge is essentially a copy that restores permissions.
-                sub.check_call(['git', 'checkout-index', '--index', '--force', fname])
+                to_checkout.append(fname)
             elif show_orphans:
                 print('Data unavailable: %s %s' % (digest, fname))
+        sub.check_call(['git', 'checkout-index', '--index', '--force'] + to_checkout)
 
     def can_clean_file(self, filename):
         '''
@@ -918,12 +896,7 @@ def pull(self, patterns=None, **kwargs):
 
         if not self.backend.pull_files(files):
             sys.exit(1)
-        # Make sure they're up to date
-        if kwargs.pop("many_binaries", False):
-            print('in accelerating mode')
-            self.checkout_all_index()
-        else:
-            self.checkout()
+        self.checkout()
 
     def push(self, unused_pattern=None, **kwargs):
         # We only want the intersection of the referenced files and ones we have cached
@@ -1090,8 +1063,6 @@ def main():
 
     sp = subparser.add_parser('pull', help='pull fatfiles from remote git-fat server')
     sp.add_argument("backend", nargs="?", help='pull using given backend')
-    sp.add_argument("--many-binaries", dest='many_binaries', action='store_true',
-                    help='accelerate pulling a repository which contains many binaries')
     sp.add_argument("patterns", nargs="*", help='files or file patterns to pull')
     sp.set_defaults(func='pull')