guix package: error: build failed: unable to fork: Invalid argument

[David Knight]

when I try:

  guix package -i hello

it downloads about 277M of files (up to guile-2.0.9.tar.xz) into
/nix/store then errors with "guix package: error: build failed: unable
to fork: Invalid argument".  Rerunning the command gives the same error
message.

The same error shows on two different distros (LFS and Gentoo on i686),
and with both Guix 0.5 and cloned from git.  Guix 0.5 'make check'
passes all tests, and the git version from today passes all tests except
'topologically-sorted, more difficult' in store.scm.  Other guix package
commands such a --search= and --list-available seem to work as expected.

A search for similar build errors came up with an 'unable to fork:
Operation not permitted' that was due to an old kernel; I'm running a
kernel 3.10.25, so I don't think it's that.

The dependencies required in the manual have the following versions:
guile (2.0.9), g++ (4.7.3), libcrypt (3.8.0), sqlite (3.8.2), libbz2
(1.0.6).

The only other error message I can see is a system log warning:

"guile: Libgcrypt warning: missing initialization - please fix the
application"