OSMesa and GLSL for ES2

I'm building mesa 9.2 with gallium, llvmpipe and ES1/2. I want to use
OSMesa with the GLSL ES 2.0. It seems to work if I modify
OSMesaCreateContextExt() like so:

-   attribs.profile = ST_PROFILE_DEFAULT;
+   attribs.profile = ST_PROFILE_OPENGL_ES2;

but that seems like a hack. Is there a proper way to use GLSL ES with OSMesa?

Thanks!
-Dale Emmons