Comment 2 for bug 986269

You can quickly test this from a terminal by mounting a partition. The first mount doesn't cause any popup. But the second does:
sudo mkdir /tmp/mnt
sudo mount /dev/sda1 /tmp/mnt
(Normal - no popup)
sudo umount /dev/sda1
sudo mount /dev/sda1 /tmp/mnt
(Now nautilus pops up showing the partition, and each subsequent time)

If you instead do this:
sudo mkdir /tmp/mnt
sudo chmod 700 /tmp/mnt
sudo mount /dev/sda1 /tmp/mnt
(Normal - no popup)
sudo umount /dev/sda1
sudo mount /dev/sda1 /tmp/mnt
(Now you get a message box with the error: Unable to open a folder for 10 GB Filesystem", "No application is registered as handling this file")