Modified to use recommended local, compact syntax

local PYTHON_VERSION=${1:-2.7.8}

Thanks for the tip.  You learn something new every day.

builds/runtimes/download_python

@@ -6,13 +6,7 @@
 # Example usage: download_python "2.7.8"
 download_python()
 {
-    PYTHON_VERSION=$1
-
-    if [ -z $PYTHON_VERSION ]
-    then
-        $PYTHON_VERSION="2.7.8"
-    fi
-
+    local PYTHON_VERSION=${1:-2.7.8}
     echo "Building Python $PYTHON_VERSION..."
     SOURCE_TARBALL="http://python.org/ftp/python/$PYTHON_VERSION/Python-$PYTHON_VERSION.tgz"
     curl -L $SOURCE_TARBALL | tar xz