ID:2116953
 
Resolved
Setting icon to null in a mutable appearance did not work correctly.
BYOND Version:511.1349
Operating System:Windows 10 Home 64-bit
Web Browser:Chrome 51.0.2704.103
Applies to:Dream Daemon
Status: Resolved (511.1350)

This issue has been resolved.
When setting the icon of a mutable_appearance to null, the mutable_appearance's icon actually gets set to (I'm guessing) the first resource in the resource cache; including those that only exist in the cache (before a clean compile).

Entire code (zip):
var blah = 'blah.dmi' // or 'blah.ogg' etc.

mob/verb/test()
var mutable_appearance/m = new (src)
world.log << "1: [m.icon] (should be null)"
m.icon = null
world.log << "2: [m.icon] (should be null)"
appearance = m
world.log << "3: [icon] (should be null, same as #2)"

Expected output:
1:  (should be null)
2: (should be null)
3: (should be null, same as #2)

Actual output:
1:  (should be null)
2: blah.dmi (should be null)
3: blah.dmi (should be null, same as #2)
Lummox JR resolved issue with message:
Setting icon to null in a mutable appearance did not work correctly.