This only happens in master, not latest stable.

Lock file (partial):

{
    "default": {
        "mypackage": {
            "git": "https://github.com/me/mypackage.git",
            "ref": "5e0042953dc91d5121f2e6960a4b063ac02b9a2c"
        }
    }
}

With v2018.11.26:

$ pipenv install
Installing dependencies from Pipfile.lock (a69852)…
To activate this project's virtualenv, run pipenv shell.
Alternatively, run a command inside the virtualenv with pipenv run.
$ ls -d .venv/lib/*/site-packages/mypackage*
.venv/lib/python3.7/site-packages/mypackage
.venv/lib/python3.7/site-packages/mypackage-0.1.0.dist-info

But with master:

$ pipenv sync
Installing dependencies from Pipfile.lock (a69852)…
Writing requirement line to temporary file: '-e file:///var/folders/sg/5486g341789bflp89sn_3qcc0000gn/T/requirementslib8k0h6371/fatek#egg=fatek'
To activate this project's virtualenv, run pipenv shell.
Alternatively, run a command inside the virtualenv with pipenv run.
$ ls -d .venv/lib/*/site-packages/mypackage*
.venv/lib/python3.7/site-packages/mypackage.egg-link
$ cat .venv/lib/python3.7/site-packages/mypackage.egg-link
/private/var/folders/sg/5486g341789bflp89sn_3qcc0000gn/T/requirementslibzdcz6kx8/mypackage/src
../