Re: [PATCH v3 10/25] Add new environment variable $GIT_COMMON_DIR

>> +'GIT_COMMON_DIR'::
>> +       If this variable is set to a path, non-worktree files that are
>> +       normally in $GIT_DIR will be taken from this path
>> +       instead. Worktree-specific files such as HEAD or index are
>> +       taken from $GIT_DIR. This variable has lower precedence than
>> +       other path variables such as GIT_INDEX_FILE,
>> +       GIT_OBJECT_DIRECTORY...
>
> For a person not familiar with "git checkout --to" or its underlying
> implementation, this description may be lacking. Such a reader may be
> left wondering about GIT_COMMON_DIR's overall purpose, and when and
> how it should be used. Perhaps it would make sense to talk a bit about
> "git checkout --to" here?