From a8c3649dd415f453736283cc9630f6557935ac34 Mon Sep 17 00:00:00 2001
From: Florian Friesdorf <flo@chaoflow.net>
Date: Wed, 27 Apr 2011 03:00:47 +0000
Subject: [PATCH] fetchgit builder rewrite to handle more cases

The old builder failed for:
- remote HEAD != master
- local repositories

svn path=/nixpkgs/trunk/; revision=26984
---
 pkgs/build-support/fetchgit/builder.sh | 27 ++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/pkgs/build-support/fetchgit/builder.sh b/pkgs/build-support/fetchgit/builder.sh
index 794b690341e3..7e363911bac1 100644
--- a/pkgs/build-support/fetchgit/builder.sh
+++ b/pkgs/build-support/fetchgit/builder.sh
@@ -2,19 +2,22 @@ source $stdenv/setup
 
 header "exporting $url (rev $rev) into $out"
 
-git clone "$url" $out
+git init $out
+cd $out
+git remote add origin "$url"
+git fetch origin
+git remote set-head origin -a
+
+# If no revision was specified, the remote HEAD will be used
+git checkout -b __nixos_build__ origin/HEAD
+
 if test -n "$rev"; then
-  cd $out
-
-  # Track all remote branches so that revisions like
-  # `t/foo@{2010-05-12}' are correctly resolved.  Failing to do that,
-  # Git bails out with an "invalid reference" error.
-  for branch in $(git branch -rl | grep -v ' origin/master$')
-  do
-    git branch --track "$(echo $branch | sed -es,origin/,,g)" "$branch"
-  done
-
-  git checkout "$rev" --
+    echo "Trying to checkout: $rev"
+    parsed_rev=$(
+        git rev-parse --verify "$rev" 2>/dev/null ||
+        git rev-parse --verify origin/"$rev" 2>/dev/null
+    ) 
+    git reset --hard $parsed_rev
 fi
 
 if test -z "$leaveDotGit"; then