According to git-fetch(1), "[t]he colon can be omitted when <dst> is empty." So according to git, the refspec "refs/heads/master" is the same as the refspec "refs/heads/master:" when fetching changes. When trying to fetch from a remote with a trailing colon with libgit2, though, the fetch actually fails while it works when the trailing colon is left out. So obviously, libgit2 does _not_ treat these two refspec formats the same for fetches. The problem results from parsing refspecs, where the resulting refspec has its destination set to an empty string in the case of a trailing colon and to a `NULL` pointer in the case of no trailing colon. When passing this to our DWIM machinery, the empty string gets translated to "refs/heads/", which is simply wrong. Fix the problem by having the parsing machinery treat both cases the same for fetch refspecs.
This is another option which we should not be keeping in the remote, but is specific to each particular operation.
Having the setting be different from calling its actions was not a great idea and made for the sake of the wrong convenience. Instead of that, accept either fetch options, push options or the callbacks when dealing with the remote. The fetch options are currently only the callbacks, but more options will be moved from setters and getters on the remote to the options. This does mean passing the same struct along the different functions but the typical use-case will only call git_remote_fetch() or git_remote_push() and so won't notice much difference.
The signature for the reflog is not something which changes dynamically. Almost all uses will be NULL, since we want for the repository's default identity to be used, making it noise. In order to allow for changing the identity, we instead provide git_repository_set_ident() and git_repository_ident() which allow a user to override the choice of signature.
This brings it in line with the rest of the lookup functions.
This lets us test this bit as well as getting closer to what they were trying to do.
With opportunistic ref updates, git has introduced the concept of having base refspecs *and* refspecs that are active for a particular fetch. Let's start by letting the user override the refspecs for download.