Performs the next rebase operation and returns the information about it. If the operation is one that applies a patch (which is any operation except GIT_REBASE_OPERATION_EXEC) then the patch will be applied and the index and working directory will be updated with the changes. If there are conflicts, you will need to address those before committing the changes.
Pointer to store the rebase operation that is to be performed next
Zero on success; -1 on failure.