texmath-0.12.5: test/roundtrip/msub-12.native

[ ESub (EIdentifier "P") (ENumber "0")
, ESymbol Rel "="
, EUnderover
    False
    (ESub (EIdentifier "P") (ENumber "0"))
    (EPhantom (EIdentifier "x"))
    (EPhantom (EIdentifier "x"))
]