I. Once off local repo setup:

  git checkout master
  git remote add -f fedora-openstack git@github.com:fedora-openstack/nova.git
    Updating fedora-openstack
    warning: no common commits
    remote: Counting objects: 81335, done.
    remote: Compressing objects: 100% (15974/15974), done.
    remote: Total 81335 (delta 65136), reused 80211 (delta 64416)
    Receiving objects: 100% (81335/81335), 85.12 MiB | 660 KiB/s, done.
    Resolving deltas: 100% (65136/65136), done.
    From github.com:fedora-openstack/nova
    * [new branch]      f16-patches -> fedora-openstack/f16-patches
    * [new branch]      master     -> fedora-openstack/master
    From github.com:fedora-openstack/nova
    * [new tag]         2011.3     -> 2011.3
    * [new tag]         2011.3.1   -> 2011.3.1
  git branch master-patches fedora-openstack/master
    Branch master-patches set up to track remote branch master from fedora-openstack.
  git remote add -f openstack git://github.com/openstack/nova.git
    Updating openstack
    remote: Counting objects: 15159, done.
    remote: Compressing objects: 100% (3992/3992), done.
    remote: Total 14587 (delta 12007), reused 12815 (delta 10480)
    Receiving objects: 100% (14587/14587), 6.43 MiB | 352 KiB/s, done.
    Resolving deltas: 100% (12007/12007), completed with 318 local objects.
    From git://github.com/openstack/nova
    * [new branch]      master     -> openstack/master
    * [new branch]      milestone-proposed -> openstack/milestone-proposed
    * [new branch]      stable/diablo -> openstack/stable/diablo
    * [new tag]         0.9.0      -> 0.9.0
    * [new tag]         2011.1rc1  -> 2011.1rc1
    * [new tag]         2011.2     -> 2011.2
    * [new tag]         2011.2gamma1 -> 2011.2gamma1
    * [new tag]         2011.2rc1  -> 2011.2rc1
    * [new tag]         diablo-1   -> diablo-1
    * [new tag]         diablo-2   -> diablo-2
    * [new tag]         diablo-3   -> diablo-3
    * [new tag]         diablo-4   -> diablo-4
    * [new tag]         essex-3    -> essex-3
    From git://github.com/openstack/nova
    * [new tag]         essex-1    -> essex-1


II. Patch set update process

Here showing how I updated fedora-openstack/master branch to essex-3 + ...

1. Ensure up to date

git fetch --all

2. Rebase our patches onto essex-3

git checkout master-patches
    Switched to branch 'master-patches'
git log --oneline # to pick sha of commit _before_ first commit to consider rebasing
# You can either rebase the patch branch onto a branch or a tag
git rebase --onto essex-3 69fcb2df
git rebase --onto remotes/openstack/stable/essex bbb021c8
# use the --interactive rebase option if want to edit/delete commits etc.

3. Pick new patches after essex-3

git log remotes/openstack/master # to find sha of other commits
git cherry-pick ed6e3efc
    [master-patches 126e601] fix `nova-manage image convert` exception
# You can also cherry pick commits from gerrit by copy and pasting the cherry-pick commands from there

4. Update the patches on master

git checkout master
    Switched to branch 'master'
./update-patches.sh
    rm '0001-Ensure-we-don-t-access-the-net-when-building-docs.patch'
    [master da3a165] Updated patches from master-patches
     1 files changed, 0 insertions(+), 25 deletions(-)
     delete mode 100644 0001-Ensure-we-don-t-access-the-net-when-building-docs.patch
    Switched to branch 'master-patches'
    Your branch and 'fedora-openstack/master' have diverged,
    and have 1747 and 281 different commit(s) each, respectively.
    Switched to branch 'master'
    Your branch is ahead of 'origin/master' by 1 commit.
    [master 0c2be04] Updated patches from master-patches
     3 files changed, 30 insertions(+), 1 deletions(-)
     create mode 100644 0002-fix-nova-manage-image-convert-exception.patch

5. Update changelog and version in spec file as appropriate and push

git commit --amend -a
fedpkg prep # to be sure to be sure the patches apply
# Note the patches generated may be fine for git apply,
# but not for the standard patch invoked by rpm.
# git handles duplicate hunks for example, so you
# may have to edit some of the patches to remove
# the already applied hunks and --amend again.
git push

6. Push updated master-patches back to github
(note the '+' below to allow non fast-forward updates)

git push fedora-openstack +master-patches:master

The same process applies for fedora-openstack/f16-patches.
Note el6 patches are not yet maintained in git, so
for now just merge from f17 (essex).
Note f17 patches are not yet maintained in git, so
for now just merge from master (essex).