This does not work because glBlitFramebuffer fails, since it is trying to blit
between FBOs with different pixel formats. This isn't allowed, check for
instance the OpenGL 3.3 core specification, section 4.3.2 or the
EXT_framebuffer_multisample specification. They unambiguously state that read
and draw framebuffer must have the same pixel format for blits that involve
multisample framebuffers.

As far as I can see, this is not a problem with Mesa, but rather with your
OpenGL compliance.