Bug#837074: Error when closing synaptic: "cannot open /etc/aptapt.conf.d/99synaptic to write APT::Install-Recommends"

[Frank de Bruijn]

Additional information: this is caused by a change in apt's 
configuration defaults, apparently in apt 1.3~rc3.
The Dir::Etc value has changed from "etc/apt/" to "etc/apt".
See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=836427. I assume 
synaptic also does not use the correct syntax to get the value (i.e. 
Dir::Etc::Parts/d).