* Add a test for nix-channel.

* Refactor the nix-channel unpacker a bit.

corepkgs/unpack-channel.sh

@@ -0,0 +1,30 @@
+mkdir $out
+mkdir $out/tmp
+cd $out/tmp
+
+inputs=($inputs)
+for ((n = 0; n < ${#inputs[*]}; n += 2)); do
+    channelName=${inputs[n]}
+    channelTarball=${inputs[n+1]}
+    
+    echo "unpacking channel $channelName"
+    
+    $bzip2 -d < $channelTarball | $tar xf -
+
+    if test -e */channel-name; then
+        channelName="$(cat */channel-name)"
+    fi
+
+    nr=1
+    attrName=$(echo $channelName | $tr -- '- ' '__')
+    dirName=$attrName
+    while test -e ../$dirName; do
+        nr=$((nr+1))
+        dirName=$attrName-$nr
+    done
+
+    mv * ../$dirName # !!! hacky
+done
+
+cd ..
+rmdir tmp