can't find crate for core

[donbright]

im building on ubuntu 18

my build line is per readme,

./bootstrap.py --crate-index /tmp/index --target-dir /tmp/out --no-clone --no-clean --target x86_64-unknown-bitrig

==========================
===== BUILDING CARGO =====
==========================

cargo:jobserver:log:cfg-if: Building cfg-if-0.1.4 (needed by: log-0.4.3)
cargo:jobserver:log:cfg-if:  PROFILE="release" TARGET="x86_64-unknown-bitrig" CARGO_MANIFEST_DIR="/tmp/out/cfg-if-0.1.4" OUT_DIR="/tmp/out" CARGO_PKG_VERSION_MAJOR="0" CARGO_PKG_VERSION="0.1.4" CARGO_PKG_VERSION_PATCH="4" HOST="x86_64-unknown-bitrig" PATH="/home/don/anaconda3/bin:/home/don/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin" DEBUG="0" OPT_LEVEL="0" CARGO_PKG_VERSION_MINOR="1" NUM_JOBS="1" CARGO_PKG_VERSION_PRE="" rustc /tmp/out/cfg-if-0.1.4/src/lib.rs --crate-name cfg_if --crate-type lib -C extra-filename=-0_1_4 --out-dir /tmp/out --emit=dep-info,link --target x86_64-unknown-bitrig -L /tmp/out -L /tmp/out/lib
cargo:jobserver:log:cfg-if: error[E0463]: can't find crate for `core`
cargo:jobserver:log:cfg-if:   |
cargo:jobserver:log:cfg-if:   = note: the `x86_64-unknown-bitrig` target may not be installed
cargo:jobserver:log:cfg-if: error: aborting due to previous error

Exception:
 from ./bootstrap.py, line 1002:
 build command failed: 101

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