I just downloaded the latest source from svn, updated all my config files/world structs, and started playing around on my server again. When using /spawn set race_type # it not only changes the targeted mob but also the player.
My client version is 4591L and using the latest source from svn.

Not sure why this has been moved to completed bugs but with revision 141 and client 5016L this still happens.

I moved it because I tested it on my server using the 5048 client I believe, and it appeared to work ok. I will move it back for further investigation.

After playing with my server today I found out that this only happens when it is used with a new mob created with /spawn create but before it is added to the DB with /spawn add. With other spawns that are already in the DB the player model is not effected, and after adding the newly created model to the DB then it will work fine, client still needs to log out to reset there model.

When you /spawn create something new, and even when you /spawn add it to the spawngroups, you still have to restart your world so it initializes all known NPCs.
So this is working then, and I can re-close it?

You can close it if you want, I just found it odd that the /spawn set race_type changed the player model even if it is on a newly created spawn. Most of the time that I used that command was on newly created spawns and I know in earlier versions of the emulator it didn't do that. I now know to save the spawn into the database right away now to avoid this minor annoyance.

Actually, let me leave it linger for a while... since you're right, we shouldn't be changing the players race even on newly created spawns.
It may just be a null reference because the spawn hasn't been initialized yet... so the feedback effect is to bounce it back on you. Good catch, nonetheless.

I don't even see an option for /spawn set race_type
anyone?

I have been able to reproduce this with different spawn set commands, specifically level and name.
It is bad for name because it changes your name and then you are unable to zone.
http://bugzilla.emagiware.com/show_bug.cgi?id=4

Resolved this issue, was a database id being 0 and applying itself to all spawns in the zone that had a database id of 0, includes players.
http://bugzilla.emagiware.com/show_bug.cgi?id=4

I believe race_type was changed to model_type not to long ago. I never noticed it with the names or levels but hopefully your fix for that will also resolve the model change.

It will be resolved, same issue.