texmath-0.12.5: test/writer/tex/msub-03.test

<<< native
[ ESub (EIdentifier "V") (ESymbol Bin "+")
, ESymbol Rel "="
, ESub
    (EIdentifier "V")
    (ESub (ESymbol Bin "+") (EPhantom (EIdentifier "fail")))
]
>>> tex
V_{+} = V_{+_{\phantom{fail}}}