texmath-0.12.5: test/writer/eqn/msub-01.test

<<< native
[ ESub (EIdentifier "L") (EIdentifier "x")
, ESymbol Rel "="
, ESub
    (EIdentifier "L")
    (EGrouped [ EIdentifier "x" , EPhantom (EIdentifier "fail") ])
]
>>> eqn
L sub x = L sub {x hphantom fail}