pip install -e

--editable

https://pip.pypa.io/en/stable/cli/pip_install/#cmdoption-e

Install a project in editable mode (i.e. setuptools “develop mode”) from a local project path or a VCS url.

VCS urlからもいける！

指定の仕方を教えてくれたエラーメッセージ

It should either be a path to a local project or a VCS URL (beginning with bzr+http, bzr+https, bzr+ssh, bzr+sftp, bzr+ftp, bzr+lp, bzr+file, git+http, git+https, git+ssh, git+git, git+file, hg+file, hg+http, hg+https, hg+ssh, hg+static-http, svn+ssh, svn+http, svn+https, svn+svn, svn+file).

venv/srcの下に入った

https://pip.pypa.io/en/latest/topics/vcs-support/#editable-vcs-installs （VCS Support (pip)内）