Work around get-pip bug

Author: njsmith

docker/build_scripts/build_utils.sh

@@ -45,7 +45,10 @@ function do_cpython_build {
     if [ -e ${prefix}/bin/python3 ]; then
         ln -s python3 ${prefix}/bin/python
     fi
-    ${prefix}/bin/python get-pip.py
+    # --force-reinstall is to work around:
+    #   https://github.com/pypa/pip/issues/5220
+    #   https://github.com/pypa/get-pip/issues/19
+    ${prefix}/bin/python get-pip.py --force-reinstall
     if [ -e ${prefix}/bin/pip3 ] && [ ! -e ${prefix}/bin/pip ]; then
         ln -s pip3 ${prefix}/bin/pip
     fi