Ubiquity waits until the driver-manager finishes before proceeding to the partitioning screen

OS: Kubuntu 14.10
Ubiquity: v2.20.0
During installation of Kubuntu, when the option to install the third-party software is selected and continue button is pressed, ubiquity does not proceed to the next screen immediately, instead it waits for the driver-manager to finish installing the third party software with only the cursor indicating a busy process. The issue here is when the internet connection is very slow (Eg. 512 kbps) and the third party software big( Eg, ~200 mb of Nvidia binary driver), it takes approximately 1 hour for the package manager to download and install the third party software. In this situation, the user is not aware of the activity since there is no progress indicator and may conclude the setup has crashed.

The system in which ubiquity was tested contained a Nvidia GT 610 graphics card

When ps aux was run from the terminal, it was observed that the driver-manager was run which called apt .

From the observation, it seems either the driver-manager or the apt is blocking the main ubiquity process.

Expected:

1. The third-party install process should not block the main install process and there by proceeding to the next install screen
2. If in case it is necessary to block the main installation process, a progress indicator should be provided for the third-party software install process.

Steps to reproduce:

1. Reduce the internet speed to 512 kbps or less
2. Have a hardware that requires a proprietary software or modify the install script to download a third party software, software that is big enough to take a long time to download.
3. Select the option "Install this third-party software"
3. Press the continue button

Note: From my observation, I strongly believe that this has nothing to do with the proprietary Nvidia driver and this bug can be reproduced without the need for a hardware that requires proprietary software by reducing the internet speed to bare minimum.