Missing core crate

[elichai]

Hi,
When I compile with xargo I get error[E0432]: unresolved import core.
I don't want to explicitly import core because that will break the regular cargo build (cargo: the name coreis defined multiple times)

I'm running RUST_TARGET_PATH=`pwd` xargo build --target x86_64-unknown-linux-sgx --release

x86_64-unknown-linux-sgx.json:

{
  "arch": "x86_64",
  "cpu": "x86-64",
  "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
  "dynamic-linking": true,
  "env": "sgx",
  "exe-allocation-crate": "alloc_system",
  "executables": true,
  "has-elf-tls": true,
  "has-rpath": true,
  "linker-flavor": "gcc",
  "linker-is-gnu": true,
  "llvm-target": "x86_64-unknown-linux-gnu",
  "max-atomic-width": 64,
  "os": "linux",
  "position-independent-executables": true,
  "pre-link-args": {
    "gcc": [
      "-Wl,--as-needed",
      "-Wl,-z,noexecstack",
      "-m64"
    ]
  },
  "relro-level": "full",
  "stack-probes": true,
  "target-c-int-width": "32",
  "target-endian": "little",
  "target-family": "unix",
  "target-pointer-width": "64",
  "vendor": "unknown"
}

Xargo.toml:

[dependencies]
alloc = {}
panic_unwind = {}
panic_abort = {}

[dependencies.std]
path = "../../xargo/my_std"
stage = 1

[dependencies.rand]
path = "../../xargo/my_rand"
stage = 2

[dependencies.my_serialize]
path = "../../xargo/my_serialize"
stage = 2