Bootstrap tests failed with local stage0 cargo and rustc
Backported changes from https://github.com/rust-lang/rust/pull/51977

From 0834d9d771e912f51deca6c25699e44734624546 Mon Sep 17 00:00:00 2001
From: Nikolai Merinov <nikolai.merinov@member.fsf.org>
Date: Mon, 2 Jul 2018 01:45:35 +0500
Subject: [PATCH] bootstrap: tests should use rustc from config.toml

Tests should always use "rustc" and "cargo" from config.toml instead
of assuming that stage0 binaries was downloaded to build directory.
---
 src/bootstrap/bootstrap.py | 2 ++
 src/bootstrap/config.rs    | 6 ++----
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/bootstrap/bootstrap.py b/src/bootstrap/bootstrap.py
index 487440becf..1701f7b83a 100644
--- a/src/bootstrap/bootstrap.py
+++ b/src/bootstrap/bootstrap.py
@@ -788,6 +788,8 @@ def bootstrap(help_triggered):
     env["BOOTSTRAP_PARENT_ID"] = str(os.getpid())
     env["BOOTSTRAP_PYTHON"] = sys.executable
     env["BUILD_DIR"] = build.build_dir
+    env["CARGO"] = build.cargo()
+    env["RUSTC"] = build.rustc()
     run(args, env=env, verbose=build.verbose)
 
 
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 6dd6291be2..d1a0deb583 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -23,7 +23,6 @@ use std::cmp;
 
 use num_cpus;
 use toml;
-use util::exe;
 use cache::{INTERNER, Interned};
 use flags::Flags;
 pub use flags::Subcommand;
@@ -362,9 +361,8 @@ impl Config {
         config.src = Config::path_from_python("SRC");
         config.out = Config::path_from_python("BUILD_DIR");
 
-        let stage0_root = config.out.join(&config.build).join("stage0/bin");
-        config.initial_rustc = stage0_root.join(exe("rustc", &config.build));
-        config.initial_cargo = stage0_root.join(exe("cargo", &config.build));
+        config.initial_rustc = Config::path_from_python("RUSTC");
+        config.initial_cargo = Config::path_from_python("CARGO");
 
         config
     }
-- 
2.17.1

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<tr><td><span title='2018-02-01 14:44:01 +0100'>2018-02-01</span></td><td><a href='/guix/commit/gnu/packages/popt.scm?id=7d1986c49f78a4a8120af1b6ee1251beccc6f92e'>gnu: gengetopt: Disable parallel tests.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2017-12-16 02:57:31 +0100'>2017-12-16</span></td><td><a href='/guix/commit/gnu/packages/popt.scm?id=afe98094dc465533c2b6b06a02be2ca62602579c'>gnu: gflags: Update to 2.2.1.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2017-09-20 20:58:04 -0400'>2017-09-20</span></td><td><a href='/guix/commit/gnu/packages/popt.scm?id=dc1d3cdef70f0e3c047c229c2a0e561d1f47bde8'>gnu: Use 'modify-phases' syntax.</a><span class='msg-avail'>...</span></td><td>Kei Kebreau</td></tr>
<tr><td><span title='2017-03-30 01:30:16 +0200'>2017-03-30</span></td><td><a href='/guix/commit/gnu/packages/popt.scm?id=6fd52309b8f52c9bb59fccffac53e029ce94b698'>gnu: Use HTTPS for almost all gnu.org HOME-PAGEs.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2017-01-21 12:44:42 +0100'>2017-01-21</span></td><td><a href='/guix/commit/gnu/packages/popt.scm?id=f07e53fb53ca2701d5051e05a7ecc95f405ec817'>gnu: gflags: Update to 2.2.0.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2016-07-21 18:09:40 -0400'>2016-07-21</span></td><td><a href='/guix/commit/gnu/packages/popt.scm?id=de67e922885baf68a746a0484ca0b45e45b0964b'>gnu: Update URLs for sourceforge.net.</a><span class='msg-avail'>...</span></td><td>Leo Famulari</td></tr>