Online installer hangs at exit when repository is not reachable

I have an online installer built with binarycreator. If I quit that installer during the "Preparing meta information download" phase because the server is not reachable, the window closes, but the installer stays running in the background.

Steps to reproduce with the "QtInstallerFramework\4.1\examples\online" example project :

1. Build the repository and installer as documented in the example's README (repogen and binarycreator).
2. Do NOT start the webserver.
3. Launch the installer.
4. Click next.
5. While the "preparing meta information download" progress bar is displayed, click on "Quit" (or on the window close button).
6. The window disappears, but the executable stays in the background indefinitely.

If the URL of the repository is a network address instead of "localhost", the executable also stays in the background, but after a while, it will start consuming CPU. This can be tested fairly easily by changing the URL of the repository to a bogus one (for example 123.123.123.123).