git gui: adding bare remotes on local filesystem reports error

Hi,

i just tried using git gui to add a remote on the local file system
and push to it.
(set Location to /tmp/blah.git, select "Initialize Remote Repository and Push")

but git gui reported:
fatal: GIT_WORK_TREE (or --work-tree=<directory>) not allowed without specifying GIT_DIR (or --git-dir=<directory>)

I bisected the error to
a9fa11fe5bd5978bb175b3b5663f6477a345d428 git-gui: set GIT_DIR and GIT_WORK_TREE after setup

I guess it is necessary to unset the GIT_DIR and GIT_WORKTREE env vars before calling
git --git-dir=$location init --bare

On a side note i am wondering why it is necessary to call mkdir -p?
And why it is not using git init --bare <path>
During some tests it created all leading directories.

Thanks,
Greetings Peter