Fix hook to run when $HOME is not explicitly set

pre-receive

@@ -30,6 +30,13 @@ if [[ $? -ne 0 ]]; then
     exit 1
 fi
 
+if [[ "x${HOME}" == "x" ]]; then
+    id=`whoami`
+    HOME=`eval echo ~${id}`
+    export HOME
+fi
+echo "HOME is ${HOME}" 1>&2
+
 tmpdir=`mktemp -d`
 tmpfile="$tmpdir/candidate"