Shallow file clobbered in partial fetch

[taralx]

I'm still trying to put together a testcase for this, but it looks like a Fetch of a subset of remote branches will cause the shallow file to be clobbered instead of updated. This results in a broken repo as some commits are unshallowed without their parents being present.

[smola]

@taralx Thank you!

I think this test case might be reproducing this bug:

• fetch only master with depth N
• fetch everything with depth >N
• master branch gets broken

There might be other variants achieving the same result.

func (s *RepositorySuite) TestBrokenMultipleShallowFetch(c *C) {
	r, _ := Init(memory.NewStorage(), nil)
	_, err := r.CreateRemote(&config.RemoteConfig{
		Name: DefaultRemoteName,
		URL:  s.GetBasicLocalRepositoryURL(),
	})
	c.Assert(err, IsNil)

	c.Assert(r.Fetch(&FetchOptions{
		Depth: 2,
		RefSpecs: []config.RefSpec{config.RefSpec("refs/heads/master:refs/heads/master")},
	}), IsNil)

	shallows, err := r.Storer.Shallow()
	c.Assert(err, IsNil)

	ref, err := r.Reference("refs/heads/master", true)
	c.Assert(err, IsNil)
	cobj, err := r.CommitObject(ref.Hash())
	c.Assert(err, IsNil)
	c.Assert(cobj, NotNil)
	err = object.NewCommitPreIterator(cobj).ForEach(func(c *object.Commit) error {
		for _, ph := range c.ParentHashes {
			for _, h := range shallows {
				if ph == h {
					return storer.ErrStop
				}
			}
		}

		return nil
	})
	c.Assert(err, IsNil)

	c.Assert(r.Fetch(&FetchOptions{
		Depth: 5,
		RefSpecs: []config.RefSpec{config.RefSpec("refs/heads/*:refs/heads/*")},
	}), IsNil)

	shallows, err = r.Storer.Shallow()
	c.Assert(err, IsNil)

	ref, err = r.Reference("refs/heads/master", true)
	c.Assert(err, IsNil)
	cobj, err = r.CommitObject(ref.Hash())
	c.Assert(err, IsNil)
	c.Assert(cobj, NotNil)
	err = object.NewCommitPreIterator(cobj).ForEach(func(c *object.Commit) error {
		for _, ph := range c.ParentHashes {
			for _, h := range shallows {
				if ph == h {
					return storer.ErrStop
				}
			}
		}

		return nil
	})
	c.Assert(err, IsNil)
}

[taralx]

Any ideas on how to fix? I think there needs to be some kind of merge/update logic in the part where we update the shallow file, but I'm not sure how it should work.

[ChrisMcKenzie]

I am experiencing this issue as well, any workaround or fix would be greatly appreciated.

[jfontan]

Can you check if #810 fixes your problems?