Don't have checkout.py's git apply_patch fail when files don't match

The contract for apply_patch is that it applies a patch on top of something, and
it either all applies cleanly or it fails.  The something that is applied on can
be as clean or dirty without having apply_patch judge.  The particular failure
condition was that we want to patch DEPS first (into the index), do some stuff,
then apply another patch on top of that.  Apply_patch was failing because it
saw that there was a DEPS in the index already when it wasn't expecting one.

A fix that could've also worked is to run git diff --staged before applying the
patch, then subtract that list from found_files, but it still gets tricky then
because what if you want to apply an independent patch on top of
an already patched index?  

Because apply_patch shouldn't need to be in the business of
keeping track of what the state of everything is like before and
after a patch (That's up to the patch application), the better thing would be to remove the assert
alltogether, and rely on "git apply" to complain if something doesn't apply.

BUG=370503
TBR=iannucci

Review URL: https://codereview.chromium.org/280023004

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@269526 0039d316-1c4b-4281-b951-d872f2087c98

checkout.py

@@ -707,10 +707,14 @@ class GitCheckout(CheckoutBase):
     found_files = self._check_output_git(
         ['diff', '--ignore-submodules',
          '--name-only', '--staged']).splitlines(False)
-    assert sorted(patches.filenames) == sorted(found_files), (
-        'Found extra %s locally, %s not patched' % (
-            sorted(set(found_files) - set(patches.filenames)),
-            sorted(set(patches.filenames) - set(found_files))))
+    if sorted(patches.filenames) != sorted(found_files):
+      extra_files = sorted(set(found_files) - set(patches.filenames))
+      unpatched_files = sorted(set(patches.filenames) - set(found_files))
+      if extra_files:
+        print 'Found extra files: %r' % (extra_files,)
+      if unpatched_files:
+        print 'Found unpatched files: %r' % (unpatched_files,)
+
 
   def commit(self, commit_message, user):
     """Commits, updates the commit message and pushes."""