mercurial: disable msan, hopefully only for a while (#1865)
mercurial: disable msan, hopefully only for a while (#1865)

Our new fuzzer requires CPython, and I'm getting extremely
confusing (and implausible-looking based on reading of CPython source)
msan issues, so let's disable msan for this project for now.
robertswiecki/oss-fuzz,skia-dev/oss-fuzz,robertswiecki/oss-fuzz,skia-dev/oss-fuzz,google/oss-fuzz,googlefonts/oss-fuzz,googlefonts/oss-fuzz,googlefonts/oss-fuzz,FeliciaLim/oss-fuzz,google/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,FeliciaLim/oss-fuzz,google/oss-fuzz,skia-dev/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,skia-dev/oss-fuzz,FeliciaLim/oss-fuzz,googlefonts/oss-fuzz,googlefonts/oss-fuzz,skia-dev/oss-fuzz,google/oss-fuzz,skia-dev/oss-fuzz,skia-dev/oss-fuzz,google/oss-fuzz,robertswiecki/oss-fuzz,googlefonts/oss-fuzz,google/oss-fuzz,google/oss-fuzz,skia-dev/oss-fuzz,robertswiecki/oss-fuzz,google/oss-fuzz,FeliciaLim/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,googlefonts/oss-fuzz,google/oss-fuzz,googlefonts/oss-fuzz,googlefonts/oss-fuzz,skia-dev/oss-fuzz,googlefonts/oss-fuzz,skia-dev/oss-fuzz,FeliciaLim/oss-fuzz,robertswiecki/oss-fuzz,google/oss-fuzz,skia-dev/oss-fuzz,google/oss-fuzz