Revert `fetch_nightly_tarball` which is used from PyPy's nightly build (fixes #546)

plugins/python-build/bin/python-build

@@ -412,6 +412,19 @@ fetch_tarball() {
   } >&4 2>&1
 }
 
+fetch_nightly_tarball() {
+  local package_name="$1"
+  local package_url="$2"
+  local package_pattern="$3"
+  fetch_tarball "$1" "$2"
+  if [ ! -e "${package_name}" ]; then
+    local nightly_package_name="$(echo ${package_pattern})"
+    if [ -e "${nightly_package_name}" ]; then
+      ln -fs "${nightly_package_name}" "${package_name}"
+    fi
+  fi
+}
+
 reuse_existing_tarball() {
   local package_filename="$1"
   local checksum="$2"