CustomLog directive in apache2.conf makes it impossible to change default logging without editing the global config.

You can and should edit apache2.conf in this case. I think the number of users who profit from a fall back access log is much higher than the number of users who want to disable the access log altogether

The problem with editing apache2.conf is that future distro changes get lost. Once you edit a config file the end user is given two options during an upgrade. They can either replace the current file with the packaged maintainer's file or keep the edited file. So either the system loses the local change or else it because distinct to a default ubuntu configuration. The greater problem is depending on which version of apache2 was installed at the point that the change was made, the configuration can look different.

If this log line was moved to a file within conf.d then I could set up a divert which over-wrote the config without disrupting the package maintainers future changes.

This bug was fixed in the package apache2 - 2.2.15-5ubuntu1

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apache2 (2.2.15-5ubuntu1) maverick; urgency=low

  * Merge from debian unstable. Remaining changes:
    - debian/{control, rules}: Enable PIE hardening.
    - debian/{control, rules, apache2.2-common.ufw.profile}: Add ufw profiles.
    - debian/control: Add bzr tag and point it to our tree.
    - debian/apache2-2.common.apache2.init: Add graceful restart (LP: #456381)
    + Dropped:
      - debian/patches/206-fix-potential-memory-leaks.dpatch: No longer needed.
      - debian/patches/206-report-max-client-mpm-worker.dpatch: No longer needed.
      - debian/config-dir/apache2.conf: Merged back from debian.
      - mod-reqtimeout functionality: Merge back from debian.
      - debian/patches/204_CVE-2010-0408.dpatch: No longer needed.
      - debian/patches/205_CVE-2010-0434.dpatch: No longer needed.
      - debian/patches/203_fix-ab-segfault.dpatch: No longer needed.

apache2 (2.2.15-5) unstable; urgency=low

  * Conflict with apache package as we now include apachectl. Closes: #579065
  * Remove conflicts with old apache 2.0 modules. The conflicts are not
    necessary anymore as skipping a stable release is not supported anyway.
  * Silence the grep in preinst.

apache2 (2.2.15-4) unstable; urgency=low

  * Move definition of other_vhosts_access.log to new config file
    /etc/apache2/conf.d/other-vhosts-access-log, but disable it
    if it has been disabled by the admin. Closes: #576572. LP: #507616
  * Comment out the contents of mods-available/proxy.conf, as it just
    is a nuisance for use of apache2 as a reverse proxy, which is much
    more common than the use as forward proxy. Extend the comments
    in the file.
  * Change defaults or add example configs for some modules:
    status.conf:
      - enable ExtendedStatus by default
      - enable ProxyStatus by default
      - document SeeRequestTail directive
    proxy_ftp.conf:
      - set 'ProxyFtpDirCharset UTF-8' by default
    ldap.conf:
      - enable /ldap-status page, allow it from localhost by default
    proxy_balancer.conf:
      - add (disabled) example for /balancer-manager page
    ssl.conf:
      - document SSLStrictSNIVHostCheck directive
  * Add symlink from apachectl to apache2ctl to be more compatible with
    upstream. Apache httpd 1.3 hasn't been in Debian for some time.
  * Simplify logrotate script. Closes: #576105
  * Remove empty directory /usr/lib/debug/usr/sbin in mpm packages.
    Closes: #576089
  * Fix apxs2 to work with perl 5.12rc3. Closes: #577239
  * Add source/format file to make lintian happy.

apache2 (2.2.15-3) unstable; urgency=low

  * mod_reqtimeout: backport bugfixes from upstream trunk up to r928881,
    including a fix for mod_proxy CONNECT requests.
  * mod_dav_fs: Use correct permissions when creating new files. LP: #540747

apache2 (2.2.15-2) unstable; urgency=low

  * Make the Files ~ "^\.ht" block in apache2.conf more secure by adding
    Satisfy all. Closes: #572075
  * mod_reqtimeout: Various bug fixes, including:
    - Don't mess up timeouts of mod_proxy's backend connections.
      Closes: #573163

apache2 (2.2.15-1) unstable; urgency=low

  * New upstream ...