Re: [PATCH 5/5] treewide: always have a valid "index_state.repo" member

> When the "repo" member was added to "the_index" in [1] the
> repo_read_index() was made to populate it, but the unpopulated
> "the_index" variable didn't get the same treatment.
> 
> Let's do that in initialize_the_repository() when we set it up, and
> likewise for all of the current callers initialized an empty "struct
> index_state".
> 
> This simplifies code that needs to deal with "the_index" or a custom
> "struct index_state", we no longer need to second-guess this part of
> the "index_state" deep in the stack. A recent example of such
> second-guessing is the "istate->repo ? istate->repo : the_repository"
> code in [2]. We can now simply use "istate->repo".
> 
> For "fsmonitor-settings.c" we can remove the initialization of a NULL
> "r" argument to "the_repository". This was added back in [3], and was
> needed at the time for callers that would pass us the "r" from an
> "istate->repo". Before this change such a change to
> "fsmonitor-settings.c" would segfault all over the test suite (e.g. in
> t0002-gitfile.sh).