How to answer to prompts automatically with python fabric?

Starting from version 1.9, Fabric includes a way of managing this properly.

The section about Prompts in the Fabric documentation says:

The prompts dictionary allows users to control interactive prompts. If
a key in the dictionary is found in a command’s standard output
stream, Fabric will automatically answer with the corresponding
dictionary value.

You should be able to make Fabric automatically answer prompts like this:

with settings(prompts={'Do you want to continue [Y/n]? ': 'Y'}):
    run('apt-get update')
    run('apt-get upgrade')