Bug: Local Variables are global for a binary and overwrites other test cases

[dsolstad]

Local variables overwrites other variables with the same name in other test cases in the same binary. For example, having output_file=file.rar in the first test case in a binary sets and overwrites this for all other test cases, so when a test case doesn't yield an output file, it might be because it overwrote file.rar in a previous test.