Teach ResolveRevision how to look up annotated tags

[novas0x2a]

This should address #772. The existing tests aren't broken by this, but I'm not quite sure how to add an annotated tag to the fixtures to add a new test for this.

[mcuadros]

Well, the tests are passing. Means that you managed to solve it, or is that were failing in your local environment?

Can you cover this change by a test?

[novas0x2a]

The correct way to add a test for this is probably to edit the fixtures and then add the relevant tests to https://github.com/src-d/go-git/blob/master/repository_test.go#L1470, but it's not clear how to do that; is there any documentation anywhere for how to regenerate https://github.com/src-d/go-git-fixtures, which seems to be the source of truth for that test?

[novas0x2a]

Any updates on this or on src-d/go-git-fixtures#1 , which this PR is kind of blocked on?

[novas0x2a]

@mcuadros?

[mcuadros]

Sorry for the late response, the fixtures can't be regenerated are immutable, if you want to cover a new case that can't be done using any of the current fixtures, you need to submit a PR with the new fixture.

The dotgit folders are a tarball of the .git and the name is the sha1 of the tar file. The packfiles are just the packfile.

The fixtures are based on https://github.com/git-fixtures/