sync: clear preciousObjects when set in error.

If this is a project that is not using object sharing (there is only one
copy of the remote project) then clear preciousObjects.

To override this for a project, run:

  git config --replace-all repo.preservePreciousObjects true

Change-Id: If3ea061c631c5ecd44ead84f68576012e2c7405c
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/350235
Reviewed-by: Jonathan Nieder <jrn@google.com>
Tested-by: LaMont Jones <lamontjones@google.com>

tests/test_subcmds_sync.py

@@ -11,9 +11,9 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
 """Unittests for the subcmds/sync.py module."""
 
+import unittest
 from unittest import mock
 
 import pytest
@@ -21,17 +21,14 @@ import pytest
 from subcmds import sync
 
 
-@pytest.mark.parametrize(
-  'use_superproject, cli_args, result',
-  [
+@pytest.mark.parametrize('use_superproject, cli_args, result', [
     (True, ['--current-branch'], True),
     (True, ['--no-current-branch'], True),
     (True, [], True),
     (False, ['--current-branch'], True),
     (False, ['--no-current-branch'], False),
     (False, [], None),
-  ]
-)
+])
 def test_get_current_branch_only(use_superproject, cli_args, result):
   """Test Sync._GetCurrentBranchOnly logic.
 
@@ -41,5 +38,49 @@ def test_get_current_branch_only(use_superproject, cli_args, result):
   cmd = sync.Sync()
   opts, _ = cmd.OptionParser.parse_args(cli_args)
 
-  with mock.patch('git_superproject.UseSuperproject', return_value=use_superproject):
+  with mock.patch('git_superproject.UseSuperproject',
+                  return_value=use_superproject):
     assert cmd._GetCurrentBranchOnly(opts, cmd.manifest) == result
+
+
+class GetPreciousObjectsState(unittest.TestCase):
+  """Tests for _GetPreciousObjectsState."""
+
+  def setUp(self):
+    """Common setup."""
+    self.cmd = sync.Sync()
+    self.project = p = mock.MagicMock(use_git_worktrees=False,
+                                      UseAlternates=False)
+    p.manifest.GetProjectsWithName.return_value = [p]
+
+    self.opt = mock.Mock(spec_set=['this_manifest_only'])
+    self.opt.this_manifest_only = False
+
+  def test_worktrees(self):
+    """False for worktrees."""
+    self.project.use_git_worktrees = True
+    self.assertFalse(self.cmd._GetPreciousObjectsState(self.project, self.opt))
+
+  def test_not_shared(self):
+    """Singleton project."""
+    self.assertFalse(self.cmd._GetPreciousObjectsState(self.project, self.opt))
+
+  def test_shared(self):
+    """Shared project."""
+    self.project.manifest.GetProjectsWithName.return_value = [
+        self.project, self.project
+    ]
+    self.assertTrue(self.cmd._GetPreciousObjectsState(self.project, self.opt))
+
+  def test_shared_with_alternates(self):
+    """Shared project, with alternates."""
+    self.project.manifest.GetProjectsWithName.return_value = [
+        self.project, self.project
+    ]
+    self.project.UseAlternates = True
+    self.assertFalse(self.cmd._GetPreciousObjectsState(self.project, self.opt))
+
+  def test_not_found(self):
+    """Project not found in manifest."""
+    self.project.manifest.GetProjectsWithName.return_value = []
+    self.assertFalse(self.cmd._GetPreciousObjectsState(self.project, self.opt))