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.
It seems that with the various recent changes to reference updating
and reflog writing, that the thread safety of refdb updates has
been reduced (either that or it was never thread safe and the
window for error has increased). Either way, this test is now
sometimes segfaulting which is no good, so let's disable the test
for now. We don't really make any public promises about thread
safety for this type of operation, so I think this is acceptable,
at least in the short term.
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.
