When a directory containing a .git directory (or even just a plain
gitlink) was found, libgit2 was going out of its way to treat it
specially. This seemed like it was necessary because the diff
code was not originally emulating Git's behavior for untracked
directories correctly (i.e. scanning for ignored vs untracked items
inside). Now that libgit2 diff mimics Git's untracked directory
behavior, the special handling for contained Git repos is actually
incorrect and this commit rips it out.
`git_submodule` objects were already refcounted internally in case
the submodule name was different from the path at which it was
stored. This makes that refcounting externally used as well, so
`git_submodule_lookup` and `git_submodule_add_setup` return an
object that requires a `git_submodule_free` when done.
This removes the fetchRecurse compiler warnings and makes the
behavior match the other submodule options (i.e. the in-memory
setting can be reset to the on-disk value).
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.