[RFC][PATCH] Remove wrong usage of GIT_DIR

[Vincent Legoll <vincent legoll gmail com>]

According to git documentation:
http://www.kernel.org/pub/software/scm/git/docs/

[...]
GIT_DIR
    If the GIT_DIR environment variable is set then it specifies a
path to use instead of the default .git for the base of the
repository.

GIT_WORK_TREE
    Set the path to the working tree. The value will not be used in
combination with repositories found automatically in a .git directory
(i.e. $GIT_DIR is not set). This can also be controlled by the
--work-tree command line option and the core.worktree configuration
variable.
[...]

and testing with git command line client:

/.../tmp/git$ cd .git
/.../tmp/git/.git$ git status --untracked-files
fatal: This operation must be run in a work tree

the usage we make of GIT_DIR environment variable in git.py is wrong
this environment variable is not pointing to a vc.root directory.

$ cd /tmp
$ mkdir gitrepo
$ mkdir gitwc
$ export GIT_DIR=`pwd`/gitrepo
$ cd gitwc
$ git init
Initialized empty Git repository in /tmp/gitrepo/
$ ls -la
total 8.0K
drwxr-xr-x 2 vince vince 4.0K 2009-04-04 19:43 .
drwxr-xr-x 4 vince vince 4.0K 2009-04-04 19:43 ..
$ ~/dev/svn/meld/trunk/meld .
fatal: This operation must be run in a work tree

Someone motivated could add proper handling of git
environment variable back.

-- 
Vincent Legoll

Index: vc/git.py
===================================================================
--- vc/git.py	(revision 1326)
+++ vc/git.py	(working copy)
@@ -41,14 +41,7 @@
 
     def __init__(self, location):
         self._tree_cache = None
-        try:
-            _vc.Vc.__init__(self, location)
-        except ValueError:
-            gitdir = os.environ.get("GIT_DIR")
-            if gitdir and os.path.isdir(gitdir):
-                self.root = gitdir
-                return
-            raise ValueError()
+        _vc.Vc.__init__(self, location)
 
     def commit_command(self, message):
         return [self.CMD,"commit","-m",message]