Hi, these three patches sort .mailmap to get consistent ordering, add nine names with proper emails to it, and then there is the third one, which contains all the joeyh changes. I put them in a separate patch in case you have other opinions about that.

I notice you're not a fan of GitHub pull requests, and attachments wasn't allowed here, so I just paste a cat 000* >all.patch here, hope that's ok. The branches are also available from https://github.com/sunny256/git-annex as the branches "edit-mailmap" (this version) and "edit-mailmap.wip" (the whole process) in case that's easier.

There will be more "useful" patches in the future, have started browsing "Learn you a Haskell for great good", it's awesome. I'll have to get the build working first, though. There is some dependency problem:

$ make
if [ "cabal " = ./Setup ]; then ghc --make Setup; fi
cabal  configure
Resolving dependencies...

Utility/Exception.hs:25:18:
    Could not find module `Control.Monad.Catch'
    Perhaps you meant
      Control.Monad.CatchIO (from MonadCatchIO-mtl-0.3.0.4)
      Control.Monad.Cont (needs flag -package mtl-2.1.1)
      Control.Monad.State (needs flag -package mtl-2.1.1)
    Use -v to see a list of the files searched for.
make: *** [Build/SysConfig.hs] Error 1

Mentioning it just in case you have a quick solution. Have tried to fix it by summoning cabal in various ways, but no luck yet. The OS used is Debian GNU/Linux 7.8 (wheezy) on x86_64.

From 20317aff9fbb8662aaeda4aa2285f92e728adc58 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=98yvind=20A=2E=20Holm?= <sunny@sunbase.org>
Date: Sat, 2 May 2015 17:22:48 +0200
Subject: [PATCH 1/3] Filter .mailmap through "sort -u" for predictability

---
 .mailmap | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.mailmap b/.mailmap
index 275b236..5d51042 100644
--- a/.mailmap
+++ b/.mailmap
@@ -1,7 +1,7 @@
 Joey Hess <id@joeyh.name> http://joey.kitenet.net/ <joey@web>
-Joey Hess <id@joeyh.name> http://joeyh.name/ <joey@web>
 Joey Hess <id@joeyh.name> http://joeyh.name/ <http://joeyh.name/@web>
+Joey Hess <id@joeyh.name> http://joeyh.name/ <joey@web>
+Richard Hartmann <richih@debian.org> https://www.google.com/accounts/o8/id?id=AItOawl9sYlePmv1xK-VvjBdN-5doOa_Xw-jH4U <Richard@web>
 Yaroslav Halchenko <debian@onerussian.com>
 Yaroslav Halchenko <debian@onerussian.com> http://yarikoptic.myopenid.com/ <site-myopenid@web>
 Yaroslav Halchenko <debian@onerussian.com> https://www.google.com/accounts/o8/id?id=AItOawnx8kHW66N3BqmkVpgtXDlYMvr8TJ5VvfY <Yaroslav@web>
-Richard Hartmann <richih@debian.org> https://www.google.com/accounts/o8/id?id=AItOawl9sYlePmv1xK-VvjBdN-5doOa_Xw-jH4U <Richard@web>
-- 
2.4.0

From b216bfdb3ab65f025e46c7fcdc86db3a3440b0af Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=98yvind=20A=2E=20Holm?= <sunny@sunbase.org>
Date: Mon, 4 May 2015 15:36:41 +0200
Subject: [PATCH 2/3] .mailmap: Add nine more uncontroversial names

Including only those with a proper email where there is no doubt about
which is the correct one.
---
 .mailmap | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/.mailmap b/.mailmap
index 5d51042..2dafcea 100644
--- a/.mailmap
+++ b/.mailmap
@@ -1,7 +1,20 @@
+Antoine Beaupré <anarcat@koumbit.org> anarcat <anarcat@web>
+Antoine Beaupré <anarcat@koumbit.org> https://id.koumbit.net/anarcat <https://id.koumbit.net/anarcat@web>
+Greg Grossmeier <greg@grossmeier.net> http://grossmeier.net/ <greg@web>
+Jimmy Tang <jtang@tchpc.tcd.ie> jtang <jtang@web>
+Joachim Breitner <mail@joachim-breitner.de> http://www.joachim-breitner.de/ <nomeata@web>
 Joey Hess <id@joeyh.name> http://joey.kitenet.net/ <joey@web>
 Joey Hess <id@joeyh.name> http://joeyh.name/ <http://joeyh.name/@web>
 Joey Hess <id@joeyh.name> http://joeyh.name/ <joey@web>
+Johan Kiviniemi <devel@johan.kiviniemi.name> http://johan.kiviniemi.name/ <Johan@web>
+Johan Kiviniemi <devel@johan.kiviniemi.name> http://johan.kiviniemi.name/ <http://johan.kiviniemi.name/@web>
+Nicolas Pouillard <nicolas.pouillard@gmail.com> http://ertai.myopenid.com/ <npouillard@web>
+Peter Simons <simons@cryp.to> Peter Simons <simons@ubuntu-12.04>
+Peter Simons <simons@cryp.to> http://peter-simons.myopenid.com/ <http://peter-simons.myopenid.com/@web>
+Philipp Kern <pkern@debian.org> http://phil.0x539.de/ <Philipp_Kern@web>
 Richard Hartmann <richih@debian.org> https://www.google.com/accounts/o8/id?id=AItOawl9sYlePmv1xK-VvjBdN-5doOa_Xw-jH4U <Richard@web>
 Yaroslav Halchenko <debian@onerussian.com>
 Yaroslav Halchenko <debian@onerussian.com> http://yarikoptic.myopenid.com/ <site-myopenid@web>
 Yaroslav Halchenko <debian@onerussian.com> https://www.google.com/accounts/o8/id?id=AItOawnx8kHW66N3BqmkVpgtXDlYMvr8TJ5VvfY <Yaroslav@web>
+Øyvind A. Holm <sunny@sunbase.org> http://sunny256.sunbase.org/ <sunny256@web>
+Øyvind A. Holm <sunny@sunbase.org> https://sunny256.wordpress.com/ <sunny256@web>
-- 
2.4.0

From b730720bf85217051b0bd6414650f3bfd5928edb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=98yvind=20A=2E=20Holm?= <sunny@sunbase.org>
Date: Mon, 4 May 2015 15:46:29 +0200
Subject: [PATCH 3/3] .mailmap: Add all variations for Joey Hess

---
 .mailmap | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/.mailmap b/.mailmap
index 2dafcea..3013a39 100644
--- a/.mailmap
+++ b/.mailmap
@@ -3,9 +3,17 @@ Antoine Beaupré <anarcat@koumbit.org> https://id.koumbit.net/anarcat <https://i
 Greg Grossmeier <greg@grossmeier.net> http://grossmeier.net/ <greg@web>
 Jimmy Tang <jtang@tchpc.tcd.ie> jtang <jtang@web>
 Joachim Breitner <mail@joachim-breitner.de> http://www.joachim-breitner.de/ <nomeata@web>
+Joey Hess <id@joeyh.name> Joey Hess <joey@gnu.kitenet.net>
+Joey Hess <id@joeyh.name> Joey Hess <joey@kitenet.net>
+Joey Hess <id@joeyh.name> Joey Hess <joeyh@debian.org>
+Joey Hess <id@joeyh.name> Joey Hess <joeyh@fischer.debian.org>
+Joey Hess <id@joeyh.name> Joey Hess <joeyh@joeyh.name>
+Joey Hess <id@joeyh.name> Joey Hess <joeyh@oberon.tam-lin.net>
+Joey Hess <id@joeyh.name> Joey Hess <joeyh@oberon.underhill.private>
 Joey Hess <id@joeyh.name> http://joey.kitenet.net/ <joey@web>
 Joey Hess <id@joeyh.name> http://joeyh.name/ <http://joeyh.name/@web>
 Joey Hess <id@joeyh.name> http://joeyh.name/ <joey@web>
+Joey Hess <id@joeyh.name> https://www.google.com/accounts/o8/id?id=AItOawmJfIszzreLNvCqzqzvTayA9_9L6gb9RtY <Joey@web>
 Johan Kiviniemi <devel@johan.kiviniemi.name> http://johan.kiviniemi.name/ <Johan@web>
 Johan Kiviniemi <devel@johan.kiviniemi.name> http://johan.kiviniemi.name/ <http://johan.kiviniemi.name/@web>
 Nicolas Pouillard <nicolas.pouillard@gmail.com> http://ertai.myopenid.com/ <npouillard@web>
-- 
2.4.0

merged --Joey

Control.Monad.Catch should be provided by the exceptions package, which there is a dependency on in the cabal file. However, building git-annex on wheezy is not supported anymore. --Joey