While upgrading to 14.04 I ran into a dependency issue `gnome-settings-daemon-schemas` which blocked the upgrade. After running `sudo apt-get -f install` I get: 

```
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Correcting dependencies... Done
The following extra packages will be installed:
  gnome-settings-daemon-schemas
The following NEW packages will be installed:
  gnome-settings-daemon-schemas
0 upgraded, 1 newly installed, 0 to remove and 530 not upgraded.
9 not fully installed or removed.
Need to get 0 B/44.2 kB of archives.
After this operation, 189 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
(Reading database ... 252639 files and directories currently installed.)
Preparing to unpack .../gnome-settings-daemon-schemas_3.8.6.1-0ubuntu11_all.deb ...
Unpacking gnome-settings-daemon-schemas (3.8.6.1-0ubuntu11) ...
dpkg: error processing archive /var/cache/apt/archives/gnome-settings-daemon-schemas_3.8.6.1-0ubuntu11_all.deb (--unpack):
 trying to overwrite '/usr/share/GConf/gsettings/gnome-settings-daemon.convert', which is also in package gnome-settings-daemon 3.10.2-0ubuntu1~saucy6

Processing triggers for gconf2 (3.2.6-0ubuntu2) ...
Errors were encountered while processing:
 /var/cache/apt/archives/gnome-settings-daemon-schemas_3.8.6.1-0ubuntu11_all.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
   Depends: gnome-settings-daemon-schemas (< 3.10) but it is not going to be installed
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

```

What has caused this and how do I progress to fix it?

---

In case it's relevant, here's the original dependency hell:

```
The following packages have unmet dependencies:
 aptitude : Depends: aptitude-common (= 0.6.8.2-1ubuntu4) but it is not going to be installed
            Depends: libboost-iostreams1.54.0 but it is not going to be installed
            Depends: libcwidget3 but it is not going to be installed
            Depends: libept1.4.12 but it is not going to be installed
 compiz-gnome : Depends: gnome-settings-daemon-schemas (>= 3.4.2-0ubuntu9) but it is not going to be installed
 unity-settings-daemon : Depends: gnome-settings-daemon-schemas (>= 3.8) but it is not going to be installed
                         Depends: gnome-settings-daemon-schemas (< 3.10) but it is not going to be installed

```