Merge branch '1.3.X' into develop

* 1.3.X:
  Update changelog and AUTHORS for Git fix.
  bugfix for git 1.8.3, in git 1.8.3 the default branch name is "detached from REVISION" when you `git checkout -q <REVISION>`. If doesn't skip it then `git rev-parse ...` will raise a error while invoking Git._get_revision_from_rev_parse method.

Conflicts:
	pip/vcs/git.py

AUTHORS.txt

@@ -2,6 +2,7 @@ Alex Grönholm
 Alex Morega
 Alexandre Conrad
 Andrey Bulgakov
+Anrs Hu
 Antti Kaihola
 Armin Ronacher
 Aziz Köksal

CHANGES.txt

@@ -23,6 +23,8 @@ Changelog
 1.3.2 (unreleased)
 ------------------
 
+* Fixed git backend with git 1.8.3. (Pull #996)
+
 * Fixed the proxy support, which was broken in pip-1.3. (Pull #840)
 
 1.3.1 (2013-03-08)