apt-check is slow because it disables pkgcache and srcpkgcache

In /usr/lib/update-notifier/apt-check:

    # force apt to build its caches in memory for now to make sure
    # that there is no race when the pkgcache file gets re-generated
    #apt_pkg.config.set("debug::pkgcachegen","1")
    apt_pkg.config.set("Dir::Cache::pkgcache","")
    apt_pkg.config.set("Dir::Cache::srcpkgcache","")

This causes apt-check to be way slower than it should be (9 seconds instead of 2.7 seconds). It was written in 2008, and the race condition that the comment refers to was fixed in 2010:

http://anonscm.debian.org/gitweb/?p=apt/apt.git;a=commitdiff;h=3010fb0e069d2fd4c7a6ade4559bfb659bf8f2fb
http://anonscm.debian.org/gitweb/?p=apt/apt.git;a=commitdiff;h=22041bd2864b8d0b401b45dde9eda4003a11fec4

So I think it’s time to remove this slow workaround.

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: update-notifier-common 0.145
ProcVersionSignature: Ubuntu 3.11.0-9.16-generic 3.11.2
Uname: Linux 3.11.0-9-generic x86_64
NonfreeKernelModules: openafs
ApportVersion: 2.12.5-0ubuntu1
Architecture: amd64
Date: Tue Oct 1 05:54:39 2013
EcryptfsInUse: Yes
InstallationDate: Installed on 2010-12-05 (1031 days ago)
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Alpha amd64 (20101202)
MarkForUpload: True
PackageArchitecture: all
SourcePackage: update-notifier
UpgradeStatus: Upgraded to saucy on 2012-11-15 (319 days ago)