I ran into this same problem. The way I solved it was by following the INSTALL instructions in 1.6.5.1. Near the bottom, it explains how to grab a copy of the pre-formatted documentation. It's pre-built, and you can get it once you've installed git. The commands are as follows:
$ mkdir manual && cd manual
$ git init
$ git fetch-pack git://git.kernel.org/pub/scm/git/git.git man html |
while read a b
do
echo $a >.git/$b
done
$ cp .git/refs/heads/man .git/refs/heads/master
$ git checkout
I actually needed another command:
git reset --hard
...but after that, it worked like a charm. I just added that directory to my $MANPATH in my ~/.bashrc like this:
# git man pages
export MANPATH="$HOME/local/git-manual:$MANPATH"
...and all the man pages work as expected. I am so happy that I got this after upgrading! Hope it works for you too...