RFH: updating gitweb packaging for Apache 2.4

[Jonathan Nieder <jrnieder@gmail.com>]

Hi,

With Apache 2.2, the gitweb package worked out of the box.  With
Apache 2.4, it doesn't.  http://bugs.debian.org/669292 tracks this
problem.

Last year, I tried to fix it --- patch at
https://bugs.debian.org/cgi-bin/bugreport.cgi?msg=23;filename=update-apache-packaging.patch;att=1;bug=669292

But I ran into several problems[*] around the upgrade path and
uninstallation procedure.  I think I understood how packaging for
apache 2.2 worked, and I just don't understand how packaging for
apache 2.4 works.

[*] https://lists.debian.org/debian-webapps/2013/12/msg00000.html

In particular:

 * It's not clear when to run "apache2_invoke enconf gitweb" for a
   package like gitweb that does not have a Depends against apache
   2.4.  If I run it conditionally based on the Apache version, then
   gitweb will still be broken when the user upgrades apache, unless
   gitweb happens to be upgraded later in the same upgrade run.

 * It's not clear when to run "apache2_invoke disconf gitweb".  At
   "remove" and "purge" time doesn't seem to be enough.

Until this is fixed, installing the gitweb package does not give the
user a usable installation of gitweb, meaning I've been sitting with
an RC bug for a long time.

Help?

Thanks,
Jonathan