[bug] Snap client _wait handles valid case as an error

[Gu1nness]

Description

The SnapClient._wait method (here) considers a valid status Do as an error while it should not.

The snapd REST API specifies that the status can be Do for "Task is ready to start".
The filtering in the SnapClient._wait only considers the cases Done and Doing, Valid as valid cases and otherwise will raise a SnapError.
Similar to this line), the status Do should sleep and wait for the task to start.

I can provide a patch if you want.

[benhoyt]

Makes sense to me. A patch would be great, thanks! Out of interest, how did you run across this? If it was due to an error, do you remember what command/operation you were running at the time?

[benhoyt]

Ah, I see you've opened #140 -- we'll take a look, thanks.

[Gu1nness]

Makes sense to me. A patch would be great, thanks! Out of interest, how did you run across this? If it was due to an error, do you remember what command/operation you were running at the time?

I'm working on the MongoDB charms and I'm refactoring everything.
As part of this refactoring, I'm using the Snap.set method to configure my snaps and I noticed that it started happening quite often (which never happened in the past), with the error message showing a status Do
A quick investigation on the REST API and the operator-libs led me to this :)