bin/56110: pkg_add can fail without an error message

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         56110
>Category:       bin
>Synopsis:       pkg_add can fail without an error message
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Apr 16 17:30:00 +0000 2021
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current, source date 2021.02.27.11.06.32
>Organization:
>Environment:
System: NetBSD
Architecture: aarch64
Machine: evbarm
>Description:

As I attempted to install a binary package on NetBSD/evbarm-aarch64
under qemu, pkg_add exited without printing an error message, giving
the impression that it had succeeded.

Yet it had clearly failed, because the exit status was nonzero (141,
suggesting an EPIPE?), and the package was left in a partially
installed state.

This PR is not about the package installation failing, as that may
have been caused by some network connectivity issue outside pkg_add's
control, but about pkg_add failing to print a message indicating that
it failed.

  arm64# pkg_add qemu
  pkg_add: Warning: package `qemu-5.2.0nb4' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  pkg_add: Warning: package `spice-server-0.14.3' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  pkg_add: Warning: package `glib2-2.66.8' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  pkg_add: Warning: package `pcre-8.44' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  Trying to reconnect https://cdn.NetBSD.org:443/pub/pkgsrc/packages/NetBSD/aarch64/9.0/All/glib2-2.66.8.tgz
  No schema files found: doing nothing.
  pkg_add: Warning: package `jpeg-9d' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  pkg_add: Warning: package `libiscsi-1.19.0' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  pkg_add: Warning: package `lzo-2.10' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  pkg_add: Warning: package `jemalloc-5.2.1nb2' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  pkg_add: Warning: package `perl-5.32.1' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  pkg_add: Warning: package `snappy-1.1.8' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  pkg_add: Warning: package `hicolor-icon-theme-0.17nb1' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  pkg_add: Warning: package `png-1.6.37' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  pkg_add: Warning: package `curl-7.76.0' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  pkg_add: Warning: package `libidn2-2.3.0' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  pkg_add: Warning: package `libunistring-0.9.10' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  pkg_add: Warning: package `nghttp2-1.43.0' was built for a platform:
  pkg_add: NetBSD/aarch64 9.0 (pkg) vs. NetBSD/aarch64 9.99.80 (this host)
  Trying to reconnect https://cdn.NetBSD.org:443/pub/pkgsrc/packages/NetBSD/aarch64/9.0/All/curl-7.76.0.tgz
  Trying to reconnect https://cdn.NetBSD.org:443/pub/pkgsrc/packages/NetBSD/aarch64/9.0/All/qemu-5.2.0nb4.tgz
  arm64# echo $?
  141
  arm64# pkg_delete qemu
  original MD5 checksum failed, not deleting: /usr/pkg/bin/qemu-ga
  pkg_delete: Couldn't remove /usr/pkg/bin/qemu-i386: No such file or directory
  pkg_delete: Couldn't remove /usr/pkg/bin/qemu-img: No such file or directory
  pkg_delete: Couldn't remove /usr/pkg/bin/qemu-io: No such file or directory
  [many more similar messages omitted]

>How-To-Repeat:

>Fix: