Remove old proc before finalising tinyipa

When building locally, if the finalise process fails, it might
happen that the old proc filesystem mounted for the chroot jail
is still there.
Unmount it before removing the old finaldir to prevent the script
to fail early.

Change-Id: I0ffe7c71ca3145202ffd5412434e6ce163df53fe

tinyipa/finalise-tinyipa.sh

@@ -57,6 +57,14 @@ fi
 
 sudo -v
 
+# Let's umount proc in case the old finalise process went sideways and
+# it's still mounted
+if grep -qs "$FINALDIR/proc" /proc/mounts; then
+    sudo umount "$FINALDIR/proc"
+fi
+
+# Remove the old final chroot dir with all its content before starting a new
+# finalise process
 if [ -d "$FINALDIR" ]; then
     sudo rm -rf "$FINALDIR"
 fi