On my mips64el-linux GuixSD system, now updated to something close to
core-updates (but with binutils-2.25.1), guile prints this warning:

  guile: warning: failed to install locale

and 'locale' prints:

  mhw@yeeloong ~$ locale
  locale: Cannot set LC_CTYPE to default locale: No such file or directory
  locale: Cannot set LC_MESSAGES to default locale: No such file or directory
  locale: Cannot set LC_ALL to default locale: No such file or directory
  LANG=en_US.utf8
  LC_CTYPE="en_US.utf8"
  LC_NUMERIC="en_US.utf8"
  [...]

strace shows attempts to open files in /run/current-system/locale/2.26,
which was not included in my built system.  Instead I have:

  /run/current-system/locale/2.26.105-g0890d5379c

This matches the version field of our 'glibc' package in core-updates,
but it's not where libc is looking.

I've attached a patch that fixes the problem for me.
What do you think?

      Mark