Environment: MSYS_BITS=64, SCRIPT=python x.py test, RUST_CONFIGURE_ARGS=--build=x86_64-pc-windows-gnu, MINGW_URL=https://s3-us-west-1.amazonaws.com/rust-lang-ci2/rust-ci-mirror, MINGW_ARCHIVE=x86_64-6.3.0-release-posix-seh-rt_v5-rev2.7z, MINGW_DIR=mingw64