another change to build script

git-svn-id: https://svn.code.sf.net/p/xcat/code/xcat-core/trunk@4513 8638fb3e-16cb-4fca-ae20-7b5d299a9bcd

buildcore.sh

@@ -174,6 +174,7 @@ fi
 mkdir -p $HOME/.gnupg
 for i in pubring.gpg secring.gpg trustdb.gpg; do
 	if [ ! -f $HOME/.gnupg/$i ] || [ `wc -c $HOME/.gnupg/$i|cut -f 1 -d' '` == 0 ]; then
+		rm -f $HOME/.gnupg/$i
 		wget -P $HOME/.gnupg $GSA/keys/$i
 		chmod 600 $HOME/.gnupg/$i
 	fi