fetchgit builder to handle broken remotes without a HEAD

svn path=/nixpkgs/trunk/; revision=27521

1 files changed, 8 insertions, 4 deletions

diff --git a/pkgs/build-support/fetchgit/builder.sh b/pkgs/build-support/fetchgit/builder.sh
index 7e363911bac1..558e946d76cf 100644
--- a/pkgs/build-support/fetchgit/builder.sh
+++ b/pkgs/build-support/fetchgit/builder.sh
@@ -1,3 +1,6 @@
+# tested so far with:
+# - no revision specified and remote has a HEAD which is used
+# - revision specified and remote has a HEAD
 source $stdenv/setup
 
 header "exporting $url (rev $rev) into $out"
@@ -6,10 +9,8 @@ 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
+git remote set-head origin -a || (
+    test -n $rev && echo "that's ok, we want $rev" || exit 1)
 
 if test -n "$rev"; then
     echo "Trying to checkout: $rev"
@@ -18,6 +19,9 @@ if test -n "$rev"; then
         git rev-parse --verify origin/"$rev" 2>/dev/null
     ) 
     git reset --hard $parsed_rev
+    git checkout -b __nixos_build__
+else
+    git checkout -b __nixos_build__ origin/HEAD
 fi
 
 if test -z "$leaveDotGit"; then