Comment 3 for bug 1460133

Can confirm this. I ran into this problem when updating squid. Muon was waiting for configuration file, and nothing else happened. Then found this report and looked at term.log:

sudo tail /var/log/apt/term.log
Configuration file '/etc/squid3/squid.conf'
 ==> Modified (by you or by a script) since installation
 ==> Package distributor has shipped an updated version.
     What would you like to do about it ? Your options are:
     Y or I : install the package maintainer's version
     N or 0 : keep your currently-installed version
         D : show the differences between the versions
         Z : start a shell to examine the situation
    The default action is to keep your current version
*** squid.conf (Y/I/N/0/D/Z) [default=N] ?