Remove 'inappropriate ioctl for device' warning

This only came up if I ran, for example
```
$ echo exit | iocsh
```

See https://unix.stackexchange.com/a/26782/445931. This assume bash,
which is safe, and fixes the issue.

require-ess/tools/iocsh_utils.py

@@ -12,7 +12,7 @@ from pathlib import Path
 @atexit.register
 def graceful_shutdown() -> None:
     print("\nExiting e3 IOC shell")
-    os.system("stty sane")
+    os.system("[[ $- == *i* ]] && stty sane")
 
 
 class TemporaryStartupScript: