nautilus process takes a considerable time to exit after closing all Files windows

Steps to reproduce

Run Files (nautilus or nautilus .) from Terminal.
Notice that you're not dropped back to the Terminal prompt, even when you close Files.

Reproducible in:

Flatpak unstable
Other: Files 3.26.3-0ubuntu4 on Ubuntu 18.04

Current behavior

Files doesn't drop the user back to Terminal prompt after closing.

Expected behavior

Files should drop the user back to Terminal prompt after closing.

Additional information

Ubuntu bug
The original reporter said that it was a problem that Files didn't drop back to prompt immediately (apparently it did before 3.4.1, how come?) but I think it can be more reasonably be raised as a problem that it doesn't drop back to Terminal prompt after being closed. I know that it remains running in the background but can the process be 'forked' (I'm guessing this is the context the original bug title meant for it) so that the user can be dropped back to the Terminal prompt when Files is closed? How useful would it be to fix this bug? Not very? Maybe this can be marked Expected Behaviour and closed?

# Steps to reproduce

1. Run Files (`nautilus` or `nautilus .`) from Terminal.
2. Notice that you're not dropped back to the Terminal prompt, even when you close Files.

Reproducible in:
<!--
    Please test if the issue was already fixed in the unstable version of the app.
    For that, follow these steps:
    1. Make sure Flatpak is installed or install it following these steps https://flatpak.org/setup
    2. Install the unstable version of the app following this link 
    https://git.gnome.org/browse/gnome-apps-nightly/plain/nautilus.flatpakref

If these steps failed, write in 'Other' the distribution you’re using and
    the version of the app.
-->
* [x] Flatpak unstable
* [x] Other: Files 3.26.3-0ubuntu4 on Ubuntu 18.04

# Current behavior

Files doesn't drop the user back to Terminal prompt after closing.

# Expected behavior

Files should drop the user back to Terminal prompt after closing.

# Additional information

[Ubuntu bug](https://bugs.launchpad.net/ubuntu/+source/nautilus/+bug/991368)<br>
The original reporter said that it was a problem that Files didn't drop back to prompt immediately (apparently it did before 3.4.1, how come?) but I think it can be more reasonably be raised as a problem that it doesn't drop back to Terminal prompt after being closed. I know that it remains running in the background but can the process be 'forked' (I'm guessing this is the context the original bug title meant for it) so that the user can be dropped back to the Terminal prompt when Files is closed? How useful would it be to fix this bug? Not very? Maybe this can be marked Expected Behaviour and closed?

Edited Dec 17, 2018 by António Fernandes