Comment # 8 on bug 1178478 from Dominique Leuenberger

(In reply to Petr Gajdos from comment #7)
> Why %() are allowed at all then?

Inside the BUILD of the package, stuff that has no impact on the bot-decided
issues, it is fine. There we are in a protected throwaway-VM, so the macros
breaking stuff are contained.

But as said: the bot does not run in such a protected environment, so it
disables macro shell execution

The critical tags for %() are:
 Name:
 Version:
 source:
 Patch:
 BuildRequires:

(and any 'if condition' that would change the presence of BuildRequires - as
the scheduler also will not execute the scripts)