init: add an option --enable-git-lfs-filter

It was reported that git-lfs did not work with git-repo. Specifically,
`git read-tree -u` run by `repo sync` would fail git-lfs's smudge
filter. See https://github.com/github/git-lfs/issues/1422.

In fact, by the time `git read-tree -u` is run, the repository is not
bare. It is just that, the working directory is not the same as the
.git directory. git-lfs's filter should work. No one seems to have
delved into that issue.

Today, with newer versions of git-repo and git-lfs, that issue will
not reproduce. Tested with
- git 2.33, git-lfs 2.13 on macOS
- git 2.17, git-lfs 2.3 on ubuntu

So, it seems fine to add an option --enable-git-lfs-filter, default to
false, and stat that it may not work with older versions of git and
git-lfs in the help doc.

Bug: https://crbug.com/gerrit/14516
Change-Id: I8d21854eeeea541e072f63d6b10ad1253b1a9826
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/328359
Tested-by: XD Trol <milestonejxd@gmail.com>
Reviewed-by: Mike Frysinger <vapier@google.com>

docs/internal-fs-layout.md

@@ -163,6 +163,7 @@ User controlled settings are initialized when running `repo init`.
 | repo.clonefilter         | `--clone-filter`          | Filter setting when using [partial git clones] |
 | repo.depth               | `--depth`                 | Create shallow checkouts when cloning |
 | repo.dissociate          | `--dissociate`            | Dissociate from any reference/mirrors after initial clone |
+| repo.git-lfs             | `--git-lfs`               | Enable [Git LFS] support |
 | repo.mirror              | `--mirror`                | Checkout is a repo mirror |
 | repo.partialclone        | `--partial-clone`         | Create [partial git clones] |
 | repo.partialcloneexclude | `--partial-clone-exclude` | Comma-delimited list of project names (not paths) to exclude while using [partial git clones] |
@@ -254,6 +255,7 @@ Repo will create & maintain a few files in the user's home directory.
 
 
 [git-config]: https://git-scm.com/docs/git-config
+[Git LFS]: https://git-lfs.github.com/
 [git worktree]: https://git-scm.com/docs/git-worktree
 [gitsubmodules]: https://git-scm.com/docs/gitsubmodules
 [manifest-format.md]: ./manifest-format.md

manifest_xml.py

@@ -666,6 +666,10 @@ https://gerrit.googlesource.com/git-repo/+/HEAD/docs/manifest-format.md
   def HasSubmodules(self):
     return self.manifestProject.config.GetBoolean('repo.submodules')
 
+  @property
+  def EnableGitLfs(self):
+    return self.manifestProject.config.GetBoolean('repo.git-lfs')
+
   def GetDefaultGroupsStr(self):
     """Returns the default group string for the platform."""
     return 'default,platform-' + platform.system().lower()

project.py

@@ -2533,8 +2533,9 @@ class Project(object):
         for key in ['user.name', 'user.email']:
           if m.Has(key, include_defaults=False):
             self.config.SetString(key, m.GetString(key))
-        self.config.SetString('filter.lfs.smudge', 'git-lfs smudge --skip -- %f')
-        self.config.SetString('filter.lfs.process', 'git-lfs filter-process --skip')
+        if not self.manifest.EnableGitLfs:
+          self.config.SetString('filter.lfs.smudge', 'git-lfs smudge --skip -- %f')
+          self.config.SetString('filter.lfs.process', 'git-lfs filter-process --skip')
         self.config.SetBoolean('core.bare', True if self.manifest.IsMirror else None)
     except Exception:
       if init_obj_dir and os.path.exists(self.objdir):

repo

@@ -149,7 +149,7 @@ if not REPO_REV:
 BUG_URL = 'https://bugs.chromium.org/p/gerrit/issues/entry?template=Repo+tool+issue'
 
 # increment this whenever we make important changes to this script
-VERSION = (2, 17)
+VERSION = (2, 21)
 
 # increment this if the MAINTAINER_KEYS block is modified
 KEYRING_VERSION = (2, 3)
@@ -382,6 +382,11 @@ def InitParser(parser, gitc_init=False):
   group.add_option('--no-clone-bundle',
                    dest='clone_bundle', action='store_false',
                    help='disable use of /clone.bundle on HTTP/HTTPS (default if --partial-clone)')
+  group.add_option('--git-lfs', action='store_true',
+                   help='enable Git LFS support')
+  group.add_option('--no-git-lfs',
+                   dest='git_lfs', action='store_false',
+                   help='disable Git LFS support')
 
   # Tool.
   group = parser.add_option_group('repo Version options')

subcmds/init.py

@@ -291,6 +291,15 @@ to update the working directory files.
     if opt.submodules:
       m.config.SetBoolean('repo.submodules', opt.submodules)
 
+    if opt.git_lfs is not None:
+      if opt.git_lfs:
+        git_require((2, 17, 0), fail=True, msg='Git LFS support')
+
+      m.config.SetBoolean('repo.git-lfs', opt.git_lfs)
+      if not is_new:
+        print('warning: Changing --git-lfs settings will only affect new project checkouts.\n'
+              '         Existing projects will require manual updates.\n', file=sys.stderr)
+
     if opt.use_superproject is not None:
       m.config.SetBoolean('repo.superproject', opt.use_superproject)