Upstream: No, not upstreamable like this
Reason: We want the rustup binary in $CARGO_HOME/bin to be of the
same version as the one we distribute in this rustup package.
--- a/src/cli/self_update.rs.1	2018-12-13 21:56:55.211778812 +0100
+++ b/src/cli/self_update.rs	2018-12-13 21:56:42.763779768 +0100
@@ -619,8 +619,7 @@
     if rustup_path.exists() {
         utils::remove_file("rustup-bin", &rustup_path)?;
     }
-    utils::copy_file(&this_exe_path, &rustup_path)?;
-    utils::make_executable(&rustup_path)?;
+    utils::hard_or_symlink_file(&this_exe_path, &rustup_path)?;
     install_proxies()
 }