{ mv test test; } should not fail

[Krzysztof Żelechowski]

Dear all:

When I say { mv test test; }, I mean that the file currently named "test" 
should be named "test" in the future.  After { mv test test; } executes, my 
wish is successfully fulfilled, so why does the command fail?!

(This breaks scripts that rename "lib" to "%{_lib}" on openSUSE, where %{_lib} 
may be "lib" or "lib64", depending on context.)

Please fix,
Chris