When `git_repository_set_head` is provided a remote reference, update
the reflog with the tag name, like we do with a branch. This helps
consumers match the semantics of `git checkout remote`.
When `git_repository_set_head` is provided a tag reference, update the
reflog with the tag name, like we do with a branch. This helps
consumers match the semantics of `git checkout tag`.
We want to use the "checkout: moving from ..." message in order to let
git know when a change of branch has happened. Make the convenience
functions for this goal write this message.
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.
The reflog append function was overzealous in its checking. When passed
an old and new ids, it should not do any checking, but just serialize
the data to a reflog entry.
The existing ones lack checking zeroed ids when switching back from an
unborn branch as well as what happens when detaching.
The reflog appending function mistakenly wrote zeros when dealing with a
detached HEAD. This explicitly checks for those situations and fixes
them.
When we update the current branch, we must also append to HEAD's reflog
to keep them in sync.
This is a bit of a hack, but as git.git says, it covers 100% of
default cases.
This is not something anybody would ever do; removing HEAD makes the
.git/ directory no longer be a repository, so we wouldn't be expected to
handle such a situation.
Any well-behaved program should write a descriptive message to the
reflog whenever it updates a reference. Let's make this more prominent
by removing the version without the reflog parameters.
