TST: Update travis-before-install.sh from master

Author: charris

tools/travis-before-install.sh

@@ -1,18 +1,14 @@
 #!/bin/bash
 
+# Exit the script immediately if a command exits with a non-zero status,
+# and print commands and their arguments as they are executed.
+set -ex
+
 uname -a
 free -m
 df -h
 ulimit -a
 
-if [ -n "$DOWNLOAD_OPENBLAS" ]; then
-  pwd
-  ls -ltrh
-  target=$(python tools/openblas_support.py)
-  sudo cp -r $target/lib/* /usr/lib
-  sudo cp $target/include/* /usr/include
-fi
-
 mkdir builds
 pushd builds
 
@@ -22,16 +18,38 @@ pip install -U virtualenv
 
 if [ -n "$USE_DEBUG" ]
 then
-  virtualenv --python=python3-dbg venv
+  virtualenv --python=$(which python3-dbg) venv
 else
   virtualenv --python=python venv
 fi
 
 source venv/bin/activate
 python -V
+gcc --version
 
 popd
 
-pip install --upgrade pip setuptools
-pip install -r test_requirements.txt
+pip install --upgrade pip
+
+# 'setuptools', 'wheel' and 'cython' are build dependencies.  This information
+# is stored in pyproject.toml, but there is not yet a standard way to install
+# those dependencies with, say, a pip command, so we'll just hard-code their
+# installation here.  We only need to install them separately for the cases
+# where numpy is installed with setup.py, which is the case for the Travis jobs
+# where the environment variables USE_DEBUG or USE_WHEEL are set. When pip is
+# used to install numpy, pip gets the build dependencies from pyproject.toml.
+# A specific version of cython is required, so we read the cython package
+# requirement using `grep cython test_requirements.txt` instead of simply
+# writing 'pip install setuptools wheel cython'.
+# urllib3 is needed for openblas_support
+pip install setuptools wheel urllib3 `grep cython test_requirements.txt`
+
+if [ -n "$DOWNLOAD_OPENBLAS" ]; then
+  pwd
+  target=$(python tools/openblas_support.py)
+  sudo cp -r $target/lib/* /usr/lib
+  sudo cp $target/include/* /usr/include
+fi
+
+
 if [ -n "$USE_ASV" ]; then pip install asv; fi