[PATCH] Documentation: always respect core.worktree if set

In the beginning, there was GIT_DIR environment variable. We had a very simple semantics:

 - When there is no GIT_DIR environment variable:

   - if "." is a "git directory", i.e. it has the set of git things like
     refs/, objects/ and HEAD, then you are working in a bare repository.

   - if ./.git exists and it is a "git directory", then "." is the top of
     the work tree;

   - otherwise, try the parent directory of "." for the second rule
     repeatedly to find the git directory and the top of the work tree.

 - When there is GIT_DIR environment variable:

   - $GIT_DIR is (and must be) the "git directory" and "." is the top of
     the work tree.

People wanted to have a work tree that is at a location totally unrelated to where the "git directory" and setting $GIT_DIR at runtime was the only way to do so, but that restricted them to work only at the top of the work tree. $GIT_WORK_TREE was invented as a way to say "this is the top of the work tree". So that people can do something like:

    $ GIT_DIR=/srv/git/proj.git GIT_WORK_TREE=/scratch/proj
    $ export GIT_DIR GIT_WORK_TREE
    $ cd $GIT_WORK_TREE/Documentation
    $ edit; git diff; git commit -a; ...

Because the facility was meant to allow separation of "git directory" and its associated work tree, and not meant to allow more than one work trees sharing the same "git directory" (which does not make any sense, as there is only one index in "git directory" that describes the state of the work tree), it was an unnecessary nuisanse that you had to set two environment variables. core.worktree was invented---by recording the location of the work tree in the config file in the "git directory", the above can be made into this:

    $ GIT_DIR=/srv/git/proj.git
    $ cd /scratch/proj/Documentation
    $ edit; git diff; git commit -a; ...

According to the current documentation, if GIT_DIR is not set, core.worktree is not respected, and the parent directory of the "git directory" may be used as worktree. This case, unless core.worktree matches the parent directory of the "git directory" in question, seems a misconfiguration and nothing else. So remove this part of the documentation.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Junio may find the description highly familiar :) only slightly modified
 at the end

 Documentation/config.txt |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)