Gentoo's Bugzilla –
Attachment 687030 Details for
Bug 771006dev-lang/rust-1.50.0 prepare fails on aarch64-gentoo-linux-musl: /var/tmp/portage/dev-lang/rust-1.50.0/temp/environment: line 3871: /var/tmp/portage/dev-lang/rust-1.50.0/work/rust-1.49.0-aarch64-unknown-linux-musl/install.sh: No such file or directory