Uh... that news makes me a bit uncomfortable. I can't currently compile latest
GIT master of MESA on openSUSE Tumbleweed, so I can't test if the problem
doesn't return because of it. I'll wait for the relevant system packages to
update and test the problematic shaders again, then post another update here.

Have you ran Second Life with Deferred Lighting enabled, EoD? It does require
an account to log in, so if you don't use it regularly it's understandable if
you can't. Would have liked knowing your results until I can test the new
commit myself though.