pipenv: Installation error from requirements.txt with -e

Still having errors, with pipenv 7.6.9, trying to port a project. Here’s a reduced/simplified case showing a reproducible error:

$ cat requirements.txt 
Flask==0.9
-e git+ssh://git@github.com/closeio/flask-sqlalchemy.git@1556d1822c46019e518707af0adc034ad4363ab4#egg=Flask-SQLAlchemy
flask-migrate==1.8.0

$ pipenv install
Creating a virtualenv for this project…
⠋New python executable in /Users/philfreo/.local/share/virtualenvs/pipenv-problem-qZknlxgQ/bin/python2.7
Also creating executable in /Users/philfreo/.local/share/virtualenvs/pipenv-problem-qZknlxgQ/bin/python
Installing setuptools, pip, wheel...done.

Virtualenv location: /Users/philfreo/.local/share/virtualenvs/pipenv-problem-qZknlxgQ
Requirements.txt found, instead of Pipfile! Converting…
Warning: Your Pipfile now contains pinned versions, if your requirements.txt did. 
We recommend updating your Pipfile to specify the "*" version, instead.
No package provided, installing all dependencies.
Pipfile.lock not found, creating…
Locking [dev-packages] dependencies…
Locking [packages] dependencies…
No handlers could be found for logger "pip.vcs.git"
Updated Pipfile.lock!
Installing dependencies from Pipfile.lock…
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An error occured while installing -e git+ssh://git@github.com/closeio/flask-sqlalchemy.git@1556d1822c46019e518707af0adc034ad4363ab4#egg=flask-sqlalchemy! Will try again.
Installing initially–failed dependencies…
Obtaining flask-sqlalchemy from git+ssh://git@github.com/closeio/flask-sqlalchemy.git@1556d1822c46019e518707af0adc034ad4363ab4#egg=flask-sqlalchemy
  Skipping because already up-to-date.
Requirement already satisfied: Flask>=0.9 in /Users/philfreo/.local/share/virtualenvs/pipenv-problem-qZknlxgQ/lib/python2.7/site-packages (from flask-sqlalchemy)
Requirement already satisfied: SQLAlchemy>=0.7 in /Users/philfreo/.local/share/virtualenvs/pipenv-problem-qZknlxgQ/lib/python2.7/site-packages (from flask-sqlalchemy)
Requirement already satisfied: Werkzeug>=0.7 in /Users/philfreo/.local/share/virtualenvs/pipenv-problem-qZknlxgQ/lib/python2.7/site-packages (from Flask>=0.9->flask-sqlalchemy)
Requirement already satisfied: Jinja2>=2.4 in /Users/philfreo/.local/share/virtualenvs/pipenv-problem-qZknlxgQ/lib/python2.7/site-packages (from Flask>=0.9->flask-sqlalchemy)
Requirement already satisfied: MarkupSafe>=0.23 in /Users/philfreo/.local/share/virtualenvs/pipenv-problem-qZknlxgQ/lib/python2.7/site-packages (from Jinja2>=2.4->Flask>=0.9->flask-sqlalchemy)
Installing collected packages: flask-sqlalchemy
  Found existing installation: Flask-SQLAlchemy 2.1

Exception:
Traceback (most recent call last):
  File "/Users/philfreo/.local/share/virtualenvs/pipenv-problem-qZknlxgQ/lib/python2.7/site-packages/pip/basecommand.py", line 215, in main
    status = self.run(options, args)
  File "/Users/philfreo/.local/share/virtualenvs/pipenv-problem-qZknlxgQ/lib/python2.7/site-packages/pip/commands/install.py", line 342, in run
    prefix=options.prefix_path,
  File "/Users/philfreo/.local/share/virtualenvs/pipenv-problem-qZknlxgQ/lib/python2.7/site-packages/pip/req/req_set.py", line 778, in install
    requirement.uninstall(auto_confirm=True)
  File "/Users/philfreo/.local/share/virtualenvs/pipenv-problem-qZknlxgQ/lib/python2.7/site-packages/pip/req/req_install.py", line 703, in uninstall
    '(at %s)' % (link_pointer, self.name, dist.location)
AssertionError: Egg-link /Users/philfreo/.local/share/virtualenvs/pipenv-problem-qZknlxgQ/src/flask-sqlalchemy does not match installed location of flask-sqlalchemy (at /Users/philfreo/Sites/foo/pipenv-problem)

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