su: ignore --preserve-environment, it's mutually exclusive to --login.

Listening on http://127.0.0.1:46225
R: src/unix/core.c:299: uv__finish_close: Assertion `0' failed.
-bash: line 1: 18906 Aborted                 R --no-save --slave -f \/opt\/shiny-server\/R\/SockJSAdapter\.R