Removing backing directory of try mode snap breaks refresh, listing (at least 2.32.3, till 2.32.5)

[Zygmunt Krynicki]

I had a snap in my home directory, installed with "snap try". This created a symlink from /var/lib/snapd/snaps/foo_x1.snap to ~zyga/foo/. I moved ~/foo to ~/Documents/foo and then tried to refresh an unrelated snap bar. Refreshing bar failed with the following message:

zyga@t470:~$ sudo snap refresh bar --edge
error: cannot refresh "bar" stat /var/lib/snapd/snaps/foo_x4.snap: no such file or directory

Moving the directory ~/Documents/foo back to ~/foo fixes everything

This issue breaks refreshes of core so I'm bumping it to critical.

[Zygmunt Krynicki (zyga)]

When this happens I saw the following message in journal:

2018/04/18 10:59:22.512843 snapmgr.go:228: cannot read snap info of snap "classic-snap-analyzer" at revision x4: stat /var/lib/snapd/snaps/classic-snap-analyzer_x4.snap: no such file or directory

I also added a regression test: https://github.com/snapcore/snapd/pull/5067

[Zygmunt Krynicki (zyga)]

This is fixed in master now. It will be out in 2.33 most likely.