Pin to known good versions of build tools

.travis.yml

@@ -11,7 +11,8 @@ matrix:
       cache:
         pip: true
       install:
-        - pip install pipenv codacy-coverage
+        - pip install -r build-requirements.txt
+        - pip install codacy-coverage
         - make
       script:
         - make lint
@@ -29,7 +30,8 @@ matrix:
       cache:
         pip: true
       install:
-        - pip install pipenv codacy-coverage
+        - pip install -r build-requirements.txt
+        - pip install codacy-coverage
         - make
       script:
         - make lint

README.md

@@ -40,6 +40,8 @@ INLOOP requires the following software:
 Using the command line, a development instance can be set up as follows:
 
 1. If you don't have it already, install [pipenv](https://docs.pipenv.org/install/).
+   If you run into trouble, the known "good" versions of the build tools are listed in
+   [build-requirements.txt](build-requirements.txt).
 
 2. Install required software with `./support/scripts/debian_setup.sh` (Debian/Ubuntu) or
    `./support/scripts/macos_setup.sh` (macOS).

build-requirements.txt

@@ -0,0 +1,3 @@
+pip==19.0.3
+pipenv==2018.11.26
+setuptools==40.8.0