This is a regression from 7.10.1 to 7.10.2-rc2.

See attachment for the result of running make TEST=conc034 WAY=optasm TEST_HC=ghc-7.10.1.20150715. It starts with:

*** Core Lint errors : in result of Simplifier ***
<no location info>: Warning:
    In the expression: seq
                         @ e10_a20g @ (# State# RealWorld, () #) e2_a20o (# eta_B1, () #)
    Kinds don't match in type application:
    Type variable: b_13 :: *
    Arg type: (# State# RealWorld, () #) :: #
    xx #
*** Offending Program ***

ghc-7.10.1 is fine. Same problem with ghc-7.11.20150711 (HEAD).