Merge #250 #251

250: fix for latest rustc r=jethrogb a=RalfJung

Fixes xargo for rust-lang/rust#63637

251: cargo update r=jethrogb a=RalfJung



Co-authored-by: Ralf Jung <post@ralfj.de>

Author: bors[bot]

.travis.yml

@@ -10,7 +10,7 @@ matrix:
       rust: nightly
       if: branch = staging OR branch = trying OR type = pull_request
     - env: TARGET=x86_64-unknown-linux-gnu
-      rust: nightly-2018-12-01
+      rust: nightly-2018-12-01 # old version without rustc-std-workspace-core
       if: branch = staging OR branch = trying
 
     # Linux (build only)