package mantis 1.2.11-1.2 [modified: usr/share/mantis/www/config_defaults_inc.php] failed to install/upgrade: subprocess installed post-installation script returned error exit status 1

[vaskoiii]

On Ubuntu 13.10

fix with:
sudo mkdir /etc/apache2/conf.d
then install the package.

It doesn't use the new format:
conf-enabled
conf-available

ProblemType: Package
DistroRelease: Ubuntu 13.10
Package: mantis 1.2.11-1.2 [modified: usr/share/mantis/www/config_defaults_inc.php]
ProcVersionSignature: Ubuntu 3.11.0-14.21-generic 3.11.7
Uname: Linux 3.11.0-14-generic x86_64
ApportVersion: 2.12.5-0ubuntu2.1
Architecture: amd64
Date: Tue Dec 17 08:55:23 2013
DuplicateSignature: package:mantis:1.2.11-1.2 [modified: usr/share/mantis/www/config_defaults_inc.php]:subprocess installed post-installation script returned error exit status 1
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationDate: Installed on 2013-12-02 (17 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
MarkForUpload: True
PackageArchitecture: all
SourcePackage: mantis
Title: package mantis 1.2.11-1.2 [modified: usr/share/mantis/www/config_defaults_inc.php] failed to install/upgrade: subprocess installed post-installation script returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)