dash opens erroneously when I quickly type a shortcut including Super key

[Adam Dingle]

I'm running Ubuntu 13.10 (Saucy).

To see the problem:

1. Use the Keyboard->Shortcuts control panel to assign a shortcut including Super to any application. For example, I assigned Super+L to the Calculator app.
2. Return to the desktop and type the shortcut quickly (pressing and releasing both keys within, say, a tenth of a second).

The dash will open (and the application you assigned the key to will appear behind it). If you type the shortcut more slowly, the dash doesn't appear.

Clearly the dash should not open unless I press the Super key by itself.