libgit2/libgit2 — pull request #974 by nulltoken (2012-10-11 17:04:29+00:00)
Title:  Enforce returning of EEXISTS when trying to overwrite a reference

This walks in the steps of c128149315c67d52c4503e294bfbd2653e0a8307 and make sure that

- `git_reference_rename()`
- `git_branch_move()`
- `git_tag_create()`
- `git_tag_create_lightweight()`

all return `GIT_EEXISTS` when the target already exists and the `force` parameter is not set.