fix bug that deletes work directory on fully persistent USB drives

tools/rc.local.sh

@@ -19,6 +19,7 @@ sudo chown -R mindstorms:mindstorms ${DOCUMENTATION_DIR}
 # in any local partition.
 # If it exists, mount it to /home/mindstorms/work.
 # Also try to find mindstorms.swp files to use as swap space.
+# Also checks for persistent drives on E2B-USB-stick
 
 mkdir -p /mnt/localfs /home/mindstorms/work
 chmod 700 /mnt
@@ -45,6 +46,7 @@ shopt -u globstar	# disallow '**' path expansion
 # Look for partition labels "casper-rw" (Easy2Boot persistence)
 echo "Looking for Easy2Boot persistence partitions..."
 E2BUDEV="/etc/udev/rules.d/999-easy2boot-permissions.rules"
+PERSISTENT=false
 rm $E2BUDEV
 for PART in /dev/disk/by-id/*; do
 	DEVICE="$( readlink -f "$PART" )"
@@ -55,6 +57,7 @@ for PART in /dev/disk/by-id/*; do
 		echo "KERNEL==\"$EASY2BOOT\", SUBSYSTEM==\"block\", SUBSYSTEMS==\"usb\", ENV{UDISKS_IGNORE}=\"1\"" >> $E2BUDEV
 		# gnome is stupid and seems to need an fstab entry
 		echo "$DEVICE /mnt/persist auto nosuid,nodev,nofail,noauto 0 0" >> /etc/fstab
+		PERSISTENT=true
 		break
 	fi
 done
@@ -134,7 +137,7 @@ for SWP in /mnt/localfs/*/mindstorms.swp; do
 done
 
 # Remove work directory if not mounted
-if ! mountpoint -q /home/mindstorms/work; then
+if [! mountpoint -q /home/mindstorms/work] && [! PERSISTENT]; then
 	echo "Removing work directory as no available mountpoint found."
 	rm -rf /home/mindstorms/work
 fi