i upvote this request!

This is possible, I think at least since version 1.2.x, maybe even since 1.1.x.

Goto page Manage > Manage Configuration > Workflow Thresholds
Uncheck column "administrator" in row "Handle an issue"

Hello Atrol, thanks for your help.

There are two ways a user can have "Adminitrator" role:
1) User is configured as "administrator" in general user prefs
2) User is assigned into a project with the administrator role.

Your suggested configuration option provides that an administrator (both cases 1 and 2) cannot assigg issues to other users, nor can be elegible for assign.

My interpretation of the original request, and the way that i understand would be useful, is that "generic administrators" (case 1), are not shown in the assign list, unless they are explicitly included in the project user list.

Your suggested configuration option provides that an administrator (both cases 1 and 2) cannot assigg issues to other users

I am not able to reproduce this (just tried latest stable version 1.2.19)