"You can only move or use one item at a time" - vendor bug

[Schneebs]

Bug Report or Feature Request (mark with an x)

- [ X ] bug report -> please search issues before submitting
- [ ] feature request

Repro steps.

1. get a char to max burden (I'm at 299%) where they cannot hold any more
2. open vendor
3. spam click buy prismatic tapers
4. try to move something (should be unable to move any item in inventory at this point)
   character remains busy until you buy the item it got stuck trying to buy

The log given by the failure.

Desired functionality.

Mention any other details that might be useful.