test-meta.sh: finish renaming variables

Apparently the changes started here weren't completely finished;
finish them:

  b836113e503ab3f8e3c30c3283eb59f936fb0023

Signed-off-by: Rob Browning <rlb@defaultvalue.org>
Tested-by: Rob Browning <rlb@defaultvalue.org>
test-meta.sh: escape user/group expressions

Escape external user/group strings before passing them to 'grep -E',
otherwise calls like this will fail when the string includes regular
expression metacharacters:

Thanks to Pierre-Emmanuel Novac <piernov@gmail.com> for reporting the
problem.

Signed-off-by: Rob Browning <rlb@defaultvalue.org>
Tested-by: Rob Browning <rlb@defaultvalue.org>
Change incorrect unknown-owners references

The test program is actually called unknown-owner (t/unknown-owner).

Signed-off-by: Rob Browning <rlb@defaultvalue.org>
Tested-by: Rob Browning <rlb@defaultvalue.org>
test-meta.sh: add missing "$() || exit $?" tests

Their omission was masking bugs fixed in several of the previous
commits.

Signed-off-by: Rob Browning <rlb@defaultvalue.org>
Tested-by: Rob Browning <rlb@defaultvalue.org>