(amd64)ubuntu@localhost:~$ sudo snappy update
Installing webdm (0.8)
Starting download of webdm
6.16 MB / 6.16 MB [=============================================================================================================] 100.00 % 263.67 KB/s 
Done
Waiting for webdm_snappyd_0.6.1.service to stop.
garbage collection impossible: prerequisites untrue: more than one active (should not happen).
(amd64)ubuntu@localhost:~$ sudo snappy list
Name           Date       Version Developer 
ubuntu-core    2015-04-23 2       ubuntu    
chatroom       2015-05-20 0.1-5   sideload  
webdm          2015-06-02 0.8               
webdm          2015-04-23 0.5     sideload  
xkcd-webserver 2015-05-20 0.5     canonical 
generic-amd64  2015-05-20 1.1.1             
(amd64)ubuntu@localhost:~$