Try just installing libmagic

bin/travis-build.bash

@@ -7,9 +7,7 @@ echo "This is travis-build.bash..."
 echo "Installing the packages that CKAN requires..."
 sudo apt-get update -qq
 sudo apt-get install postgresql-$PGVERSION solr-jetty libcommons-fileupload-java:amd64=1.2.2-1
-
-aptitude search libmagic
-aptitude show libmagic1
+sudo apt-get install libmagic
 
 echo "Installing CKAN and its Python dependencies..."
 git clone https://github.com/datagovuk/ckan