Invoking vim from inside Cursive session

Asking for help
# Problem description
Invoking vim from inside a cursive session
During a cursive session:
```
let mut cmd = Command::new("vi").arg(fname).spawn()?;
cmd.wait()?;
```
Calling the above opens a vi session with the file but on closing vi, the cursive program also closes.

# Environment

* Operating system: Ubuntu 18.04
* Backend used: ncurses
* ncursew 6.1
* Current locale (run `locale` in a terminal).
```
LANG=en_IN
LANGUAGE=
LC_CTYPE="en_IN"
LC_NUMERIC="en_IN"
LC_TIME="en_IN"
LC_COLLATE="en_IN"
LC_MONETARY="en_IN"
LC_MESSAGES="en_IN"
LC_PAPER="en_IN"
LC_NAME="en_IN"
LC_ADDRESS="en_IN"
LC_TELEPHONE="en_IN"
LC_MEASUREMENT="en_IN"
LC_IDENTIFICATION="en_IN"
LC_ALL=

```
* Cursive version (from crates.io, from git, ...)
Cursive 0.12.0