Re: `git rev-parse --is-inside-work-tree` and $GIT_WORK_TREE

> So, I find this behaviour a little strange; I can't determine if it's
> a subtle bug, or intentionally undefined/‘fuzzy’ behaviour:
> 
>     $ cd a-repo/.git/
>     $ pwd
>     /path/to/a-repo/.git
>     $ git rev-parse --is-inside-work-tree
>     false
>     $ export GIT_WORK_TREE=/path/to/a-repo
>     $ git rev-parse --is-inside-work-tree
>     true
> 
> i.e. when within the repository (the `.git` directory), and when that
> directory is a sub-directory of the working-tree, `rev-parse
> --is-inside-work-tree` reports *false* (reasonable enough, I suppose);
> but then if `$GIT_WORK_TREE` is set to precisely the directory that
> git was *already* assuming was the working-directory, then the same
> command, in the same location, reports *true*.
> 
> This should probably be made consistent: either `rev-parse
> --is-inside-work-tree` should report “true”, even inside the `.git`
> dir, as long as that directory is a sub-directory of the working-tree
> … or repository-directories / `$GIT_DIR` / `.git` directories should
> be excluded from truthy responses to `rev-parse
> --is-inside-work-tree`.