use PYTHON_EXE not python, work around issue with multibuild not doing same

Author: mattip

config.sh

@@ -4,6 +4,16 @@
 source gfortran-install/gfortran_utils.sh
 
 function build_wheel {
+    # Work around bug in multibuild, until this is merged
+    # https://github.com/matthew-brett/multibuild/pull/315
+    if [ "${PYTHON_VERSION:0:4}" == "pypy" -a "$PYTHON_EXE" != "$(readlink -f python)" ]; then
+        # possibly create a symbolic link if using pypy
+        ln -s $PYTHON_EXE $(dirname "$PYTHON_EXE")/python
+    fi
+    if [ "$(readlink -f $PYTHON_EXE)" != "$(readlink -f python)" ]; then
+        echo expected python to be "$PYTHON_EXE" not "$(readlink -f python)"
+        exit 1
+    fi
     local lib_plat=$PLAT
     if [ -n "$IS_OSX" ]; then
         install_gfortran
@@ -21,8 +31,8 @@ function build_libs {
     # download and un-tar the openblas libraries. The python call returns
     # the un-tar root directory, then the files are copied into /usr/local.
     # Could utilize a site.cfg instead to prevent the copy.
-    python -mpip install urllib3
-    basedir=$(python numpy/tools/openblas_support.py)
+    $PYTHON_EXE -mpip install urllib3
+    basedir=$($PYTHON_EXE numpy/tools/openblas_support.py)
     $use_sudo cp -r $basedir/lib/* /usr/local/lib
     $use_sudo cp $basedir/include/* /usr/local/include
 }
@@ -39,10 +49,10 @@ function run_tests {
     if [ -z "$IS_OSX" ]; then
         apt-get -y update && apt-get install -y gfortran
     fi
-    python -c "$(get_test_cmd)"
+    $PYTHON_EXE -c "$(get_test_cmd)"
     # Check bundled license file
-    python ../check_license.py
+    $PYTHON_EXE ../check_license.py
     # Show BLAS / LAPACK used. Since this uses a wheel we cannot use
     # tools/openblas_config.py; tools is not part of what is shipped
-    python -c 'import numpy; numpy.show_config()'
+    $PYTHON_EXE -c 'import numpy; numpy.show_config()'
 }