fix fedora release

Signed-off-by: Jessica Frazelle <princess@docker.com>

hack/install.sh

@@ -140,12 +140,12 @@ do_install() {
 	fi
 	if [ -z "$lsb_dist" ] && [ -r /etc/fedora-release ]; then
 		lsb_dist='fedora'
-		dist_version="$(rpm -qa \*-release | cut -d"-" -f3)"
+		dist_version="$(rpm -qa \*-release | cut -d"-" -f3 | head -n1)"
 	fi
 	if [ -z "$lsb_dist" ]; then
 		if [ -r /etc/centos-release ] || [ -r /etc/redhat-release ]; then
 			lsb_dist='centos'
-			dist_version="$(rpm -qa \*-release | cut -d"-" -f3)"
+			dist_version="$(rpm -qa \*-release | cut -d"-" -f3 | head -n1)"
 		fi
 	fi
 	if [ -z "$lsb_dist" ] && [ -r /etc/os-release ]; then