Try not using the -f flag. It attempts to "fix-broken" to deduce what isn't working and either eliminate it or perform some other action. It should really only be used if you're troubleshooting a bad package install or some other installation issue. A normal package install should be of the type:
sudo apt-get install package
It would help if you listed the package you were actually trying to install, though.
Listed in the error was this package:
So perhaps try deleting that file (or moving it to another location, say /tmp) and rerun your install. If aptitude has downloaded that deb file (but it is corrupt) it could be trying to install it as a dependency. You may also delete that file and try to install "python-gi" again, or whatever that package's name is.