The value of get_config_var("SO") is the same as before, something like ".cpython-32.so" by default on Linux. (see, I just moved the line SO=.$SOABI$SO at the bottom of the patch).

In the C file dynload_shlib.c, I chose the names SO_BASE for the "simple" extension (.so) and SO_EXTRA for the "decorated" extension (.cpython-32.so)

Is there a way to write unit tests for all this? This would prove that the default behavior is the same as before.