[v2 1/3] thread.cc: Avoid empty thread names if possible.

[David Bremner]

Jesse Rosenthal <jrosenthal at jhu.edu> writes:

>  
> +#define EMPTY_STRING(s) ((s)[0] == '\0') 
> +

Extra whitespace at end of line. If that's the only issue I can rebase
it away, but maybe you want to enable the standard pre-commit hook?

>  struct visible _notmuch_thread {
>      notmuch_database_t *notmuch;
>      char *thread_id;
> @@ -330,11 +332,13 @@ _thread_set_subject_from_message (notmuch_thread_t 
> *thread,
>      } else {
>       cleaned_subject = talloc_strdup (thread, subject);
>      }
> +    
Same here. 

>