regression test for #205
remove unused set_vars, but there are still set_vars that shouldn't be in defined_names, #205
Jedi doesn't support del yet
assignment details description
temporarily disable old tests to refactor set_vars
preparation to get rid of set_vars
get rid of set_vars parent setting (use token_list instead).
generate set_vars now
use as_names as a way to inject 'set_vars' to statements