wrap ./configure in a wrapper saving conftest.py

as autoconf's generated configure clobbers conftest*,
we are saving conftest.py from it by making a backup copy and then
restoring it after the real configure was run.

Author: dimpase

.gitignore

@@ -18,6 +18,7 @@
 /config.log
 /config.status
 /configure
+/real_configure
 /confdefs.h
 
 /m4/sage_spkg_configures.m4

bootstrap

@@ -329,3 +329,5 @@ fi
 if [ $SAVE = yes ]; then
     save
 fi
+mv configure real_configure
+cp configure_wrapper configure

configure_wrapper

@@ -0,0 +1,4 @@
+#! /bin/sh
+cp conftest.py bak_conftest.py
+./real_configure $@
+mv bak_conftest.py conftest.py