pkg/54453: lang/rust installs incomplete on NetBSD 8.1/amd64

[joernc%gmail.com@localhost]

>Number:         54453
>Category:       pkg
>Synopsis:       lang/rust installs incomplete on NetBSD 8.1/amd64
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Aug 10 16:55:00 +0000 2019
>Originator:     Joern Clausen
>Release:        8.1
>Organization:
>Environment:
>Description:
lang/rust builds and installs without error on NetBSD 8.1/amd64, but the package is incomplete:

$ pkg_info -L rust-1.36.0
Information for rust-1.36.0:

Files:
/vol/pkg/20190803/etc/bash_completion.d/cargo
/vol/pkg/20190803/man/man1/cargo-bench.1
/vol/pkg/20190803/man/man1/cargo-build.1
/vol/pkg/20190803/man/man1/cargo-check.1
...
/vol/pkg/20190803/man/man1/cargo.1
/vol/pkg/20190803/man/man1/rustc.1
/vol/pkg/20190803/man/man1/rustdoc.1

i.e. essentially only man-pages are installed. work/rust-bootstrap seems to contain binaries and other stuff that was built successfully, especially bin/rustc and bin/cargo.
>How-To-Repeat:
I have bootstrapped pkgsrc with an unprivileged user outside /usr/pkgsrc and do not install to /usr/pkg (see this thread for context: https://mail-index.netbsd.org/netbsd-users/2019/08/08/msg023310.html). At the moment I don't have the resources (disk space) to repeat the build with standard paths.
>Fix: