tests fail with Bats 0.4.0, which is latest in EPEL

[reidpr]

The test suite fails with Bats version 0.4.0, which is what's currently in EPEL (sstephenson/bats@3b33a5a):

 ✗ broken image errors
   (in test file run/ch-run_misc.bats, line 582)
     `rm "${img}/${f}"' failed
   ch-run[19016]: can't execve(2): /bin/true: No such file or directory (charliecloud.c:476 2)
   required: etc/group etc/passwd
   rm: cannot remove '/tmp/bats.tmp.charlie/broken-image/etc/group etc/passwd': No such file or directory

The problem is that Bats' run command does not restore $IFS, so word breaking no longer works after you call it. This was fixed in PR sstephenson/bats#90, but the EPEL package does not have that PR.

The embedded Bats via our Git submodule works because it's Git master and does have the PR, but we want to get rid of embedded Bats.

We want the test suite to pass using readily available Bats, which it currently does not on RHEL/CentOS/Fedora.

I see two options:

1. Wrap Bats run to restore $IFS. This would make EPEL Bats work, but adds cruft to our code.
2. Require a Bats with the bug fix in question. This would have less cruft but require:
   • Update the Bats RPM. Currently it is unmaintained, and may be replaced with Bats-core, which does seem to have the bug fix. (Bats is no longer maintained upstream, and Bats-core is a maintained fork.)
   • Test that the Bats in use does not have the bug.
   • Document the required Bats version, which is more complicated than stating a simple version number.

[reidpr]

Note that Debian Stretch (9) and Buster (10) both have the buggy Bats as well, and it seems Debian Bullseye (11) will have Bats-core.