Enabling additional repositories does not trigger update of available packages

[iGadget]

It's possible that what I'm describing below are actually 2 bugs. If so, feel free to correct me.

On my freshly installed Ubuntu 12.04, there is no way for me to install i.e. Skype from SC without additional measures because the info on available packages is not updated when adding a repository. Also, there is no graphical way in SC to trigger this update. I need to do a 'sudo apt-get update' in the console before any packages of the newly added repo are shown.

Steps to reproduce:
1) Install Ubuntu (in my case I installed 12.04.1 an ran all updates)
2) Open SC
3) Search for 'skype'

No appropriate results are shown (isn't this a bug by itself? Shouldn't SC at least show Skype and prompt me to enable the Partner repo when I try to install it?).

4) Go to Edit -> Software Sources
5) Go to tab 'Other Software'
6) Enable 'Canonical Partners'
7) Enter your password
8) Click 'Close'
9) Now search for 'skype' again

Result: No appropriate results are shown.

Expected result: available packages info is updated automatically OR the system prompts me to do so.

To confirm that indeed the package info of the Partner repo has not been updated:
1) Click on the right side of 'All Software' to reveal the drop-down menu
2) Choose 'Canonical Partners'
3) Notice no results are being shown.

Since there is no way to trigger the update of available packages in SC (is there?), the only workaround is:
1) Open a Terminal
2) Type 'sudo apt-get update' and hit Enter
3) Enter your password and hit Enter
4) Close SC
5) Open SC
6) Wait a few moments (SC seems to be slow in picking up changes)
7) Search for 'skype'

Skype now finally appears and can be installed.

Output of lsb_release -rd:
Description: Ubuntu 12.04.2 LTS
Release: 12.04

Output of apt-cache policy software-center:
software-center:
  Installed: 5.2.7
  Candidate: 5.2.7
  Version table:
 *** 5.2.7 0
        500 http://nl.archive.ubuntu.com/ubuntu/ precise-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     5.2 0
        500 http://nl.archive.ubuntu.com/ubuntu/ precise/main amd64 Packages

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.