CVE-2020-15101: freewvs's nested directory structure can interrupt scan

The vulnerability stems from the use of os.walk() in the main directory scanning loop without recursion depth control. Python's os.walk() uses recursion internally, and the original implementation allowed unlimited directory nesting. When scanning a directory with >1000 nested subdirectories, this would hit Python's recursion limit, crashing the scan. The commit fixed this by adding a check on root.count(os.sep) to limit recursion depth. The vulnerable code is explicitly shown in the diff as the unmodified os.walk() loop in the 'freewvs' file's main scanning logic.