* gash/environment.scm (initial-variables): Add 'SHELL' and 'SHELLOPTS'.
* tests/100-cd.sh, tests/100-cd.stdout: Use '/tmp' instead of '/bin'.
* tests/50-redirect-in-out.sh, tests/50-redirect-space.sh,
tests/50-redirect.sh: Use '/tmp' and PID for temporary files.
* tests/50-redirect-sed.sh: Make sure 'DESTDIR' is unset and use
'/bin/GASH' in place of '/bin/gash'.
* tests/50-redirect-sed.stdout, tests/data/diff.scm: Use '/bin/GASH' in
place of '/bin/gash'.
* Makefile.am (FULL_TESTS): Add tests/50-redirect-sed.sh,
tests/50-redirect-space.sh, and tests/100-cd.sh; remove
tests/50-redirect-merge.sh.
(BROKEN_TESTS): Remove tests/10-if-redirect.sh,
tests/50-redirect-sed.sh, tests/50-redirect-space.sh, and
tests/100-cd.sh; add tests/50-redirect-merge.sh.
Co-authored-by: Timothy Sample <samplet@ngyro.com>