[PATCH] lua: fix tarantool -e "os.exit()" hang.

[Serge Petrenko]

After the patch which made os.exit() execute on_shutdown triggers
(see commit 6dc4c8d7b5b40d66fe0451ef4d1f4bdf4d2cf60e) we relied
on on_shutdown triggers to break the ev_loop and exit tarantool.
Hovewer, there is an auxiliary event loop which is run in
tarantool_lua_run_script() to reschedule the fiber executing chunks
of code passed by -e option and executing interactive mode.
This event loop is started only to execute interactive mode, and
doesn't exist during execution of -e chunks. Make sure we don't start
it if os.exit() was already executed in one of the chunks.

Closes #3966
---
https://github.com/tarantool/tarantool/issues/3966
https://github.com/tarantool/tarantool/tree/sp/gh-3966-os-exit-hang

 src/lua/init.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/lua/init.c b/src/lua/init.c
index ca4b47f3a..d18c8af94 100644
--- a/src/lua/init.c
+++ b/src/lua/init.c
@@ -664,7 +664,8 @@ tarantool_lua_run_script(char *path, bool interactive,
 	 * Run an auxiliary event loop to re-schedule run_script fiber.
 	 * When this fiber finishes, it will call ev_break to stop the loop.
 	 */
-	ev_run(loop(), 0);
+	if (start_loop)
+		ev_run(loop(), 0);
 	/* The fiber running the startup script has ended. */
 	script_fiber = NULL;
 }
-- 
2.17.2 (Apple Git-113)