llvm dev - Jun 2010 - [LLVMdev] Why adding the flag --disable-assertions to configure makes the build Release+Asserts ?

I have these flags that make Release build:
configure --prefix=/my/prefix --enable-shared --enable-libffi 
--disable-debug-runtime --disable-debug-symbols --enable-optimized

But when I add --disable-assertions printed output begins to show: 
Release+Asserts

This doesn't make sense.

Yuri