Run dialog doesn't process arguments properly

[Alkis Georgopoulos]

I press Alt+F2 to invoke Unity's Run dialog, and I type the following:
x-terminal-emulator -e sh -c 'date && bash'

In all the other desktop environments, like GNOME, KDE, MATE, XFCE, LXDE, this invokes a terminal that shows the date and gives a bash prompt.

Unity's Run dialog can't process quotes properly, so it fails.
Of course this is just an example, the Run dialog argument processing is quite broken in general.

This happens in both 14.04 and 16.04 fully updated.