Error alert says "Go to the repository dialog" but doesn't let you

synaptic 0.75.5, Ubuntu 12.04 beta 1

1. echo "deb http://ppa.launchpad.net/tualatrix/ppa/ubuntu main #Ubuntu Tweak Stable Source" | sudo tee /etc/apt/sources.list.d/ubuntu-tweak-stable.list
2. synaptic

What happens:
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An error occurred
The following details are provided:
E: Malformed line 1 in source list /etc/apt/sources.list.d/ubuntu-tweak-stable.list (dist parse)
E: The list of sources could not be read.
Go to the repository dialog to correct the problem.
E: _cache->open() failed, please report.
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* The only button in the error alert is "Close".
* In Ubuntu 10.10 and later, there is no graphical way to get to "the repository dialog", since Ubuntu Software Center and Update Manager won't open either.

What should happen: If Synaptic will continue to ever suggest that you "go to the repository dialog", the error alert should contain a button for actually doing that.

To recover:
3. sudo rm /etc/apt/sources.list.d/ubuntu-tweak-stable.list

The equivalent bug in Update Manager is bug 633316, and in Ubuntu Software Center is bug 633626.