Tests failing on some hosts because 'cat' is mocked

[D0han]

./run_tests.sh
Running test_cat_mockmaker.sh test suite
Checking stdout..
Checking stderr..
Checking exitcode..

Running test_echo_special.sh test suite
Checking stdout..
Checking stderr..
Checking exitcode..

Running test_git_help.sh test suite
Checking stdout..
Checking stderr..
Checking exitcode..

Running test_git_thiswillfail.sh test suite
Checking stdout..
Checking stderr..
Checking exitcode..

Running test_git_version.sh test suite
Checking stdout..
Checking stderr..
Checking exitcode..

Running test_unknown_args.sh test suite
ERROR: ./cat test_unknown_args_stdout.txt is not mocked
ERROR: ./cat test_unknown_args_stderr.txt is not mocked
FAIL: stderr is empty
ERROR: Test failed: test_unknown_args.sh

Running test_unknown_command.sh test suite

Running shellcheck_test_mockmaker.sh test suite

Running shellcheck_test_mocks.sh test suite

Running shellcheck_test_tests.sh test suite

You can skip shellcheck tests with --skip-shellcheck

Mocked 'cat' is used instead of system one for test internals. This should not be the case.