Fix mount_shares fail on double start

mount_shares.sh

 #!/bin/bash
-[ `grep -c "/^\/\/ecole-dc/" /etc/mtab` -gt 0 ] && exit 0
+[ `grep -c '^//ecole-dc/' /etc/mtab` -gt 0 ] && exit 0
 awk '/^\/\/ecole-dc/{print $2}' /etc/fstab | \
 	while read dest
 do