message: fix auto-toolchain pwd
diff: @@ -59,7 +59,7 @@ if [ -z "$AUTO_OPS" ]; then
  # Run this first, so that the toolchain doesn't change after
  # other code has run.
  if [ -f "$MIRIDIR/.auto-everything" ] || [ -f "$MIRIDIR/.auto-toolchain" ] ; then
  - "$MIRIDIR"/rustup-toolchain
  + (cd "$MIRIDIR" && ./rustup-toolchain)
  fi
  if [ -f "$MIRIDIR/.auto-everything" ] || [ -f "$MIRIDIR/.auto-fmt" ] ; then
  