Install works as editable but not regular
I'm in a different directory as my main library in a different virtualenv. It works when I do a `pip install -e` install but not a regular (no `-e` flag) install:

```
~/D/P/R/coronavirus_genome_phylogeny ❯❯❯ pip install ../librtd/librtd-py
Processing /Users/BenjaminLee/Desktop/Python/Research/librtd/librtd-py
Processing /Users/BenjaminLee/Library/Caches/pip/wheels/9b/04/dd/7daf4150b6d9b12949298737de9431a324d4b797ffd63f526e/docopt-0.6.2-py2.py3-none-any.whl
Building wheels for collected packages: librtd
  Building wheel for librtd (setup.py) ... done
  Created wheel for librtd: filename=librtd-0.0.1-cp37-cp37m-macosx_10_15_x86_64.whl size=141098 sha256=549d98793215bc354b3faf5eb7a37b10ac530be44e11da67a6b0d5315b978dab
  Stored in directory: /Users/BenjaminLee/Library/Caches/pip/wheels/29/7f/c4/4fba79502ea438c55740cfddce1b8f317ce3078f8913bae1fc
Successfully built librtd
Installing collected packages: docopt, librtd
Successfully installed docopt-0.6.2 librtd-0.0.1
WARNING: You are using pip version 20.1; however, version 20.2 is available.
You should consider upgrading via the '/Users/BenjaminLee/.virtualenvs/corona/bin/python3.7 -m pip install --upgrade pip' command.
~/D/P/R/coronavirus_genome_phylogeny ❯❯❯ rtd
Traceback (most recent call last):
  File "/Users/BenjaminLee/.virtualenvs/corona/bin/rtd", line 5, in <module>
    from cli_wrapper import cli_wrapper
ModuleNotFoundError: No module named 'cli_wrapper'
~/D/P/R/coronavirus_genome_phylogeny ❯❯❯ pip install ../librtd/librtd-py^C
~/D/P/R/coronavirus_genome_phylogeny ❯❯❯ python
Python 3.7.7 (default, Mar 18 2020, 19:38:56)
[Clang 11.0.0 (clang-1100.0.33.17)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import librtd
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'librtd'
>>>
KeyboardInterrupt
>>>
~/D/P/R/coronavirus_genome_phylogeny ❯❯❯ pip uninstall ../librtd/librtd-py
ERROR: You must give at least one requirement to uninstall (see "pip help uninstall")
~/D/P/R/coronavirus_genome_phylogeny ❯❯❯ pip uninstall librtd
Found existing installation: librtd 0.0.1
Uninstalling librtd-0.0.1:
  Would remove:
    /Users/BenjaminLee/.virtualenvs/corona/bin/rtd
    /Users/BenjaminLee/.virtualenvs/corona/lib/python3.7/site-packages/cli.cpython-37m-darwin.so
    /Users/BenjaminLee/.virtualenvs/corona/lib/python3.7/site-packages/librtd-0.0.1.dist-info/*
    /Users/BenjaminLee/.virtualenvs/corona/lib/python3.7/site-packages/librtdpy.cpython-37m-darwin.so
Proceed (y/n)? y
  Successfully uninstalled librtd-0.0.1
~/D/P/R/coronavirus_genome_phylogeny ❯❯❯ pip install -e ../librtd/librtd-py
Obtaining file:///Users/BenjaminLee/Desktop/Python/Research/librtd/librtd-py
Requirement already satisfied: docopt in /Users/BenjaminLee/.virtualenvs/corona/lib/python3.7/site-packages (from librtd==0.0.1) (0.6.2)
Installing collected packages: librtd
  Running setup.py develop for librtd
Successfully installed librtd
WARNING: You are using pip version 20.1; however, version 20.2 is available.
You should consider upgrading via the '/Users/BenjaminLee/.virtualenvs/corona/bin/python3.7 -m pip install --upgrade pip' command.
~/D/P/R/coronavirus_genome_phylogeny ❯❯❯ rtd
Usage:
rtd <k> <input> [<output>] [--reverse-complement|--pairwise]
rtd (-h | --help)
rtd --version
~/D/P/R/coronavirus_genome_phylogeny ❯❯❯
```

Any idea why that would be?