The license specified in a LICENSE or COPYING file may not match the rest of the source code. Debian's devscripts package has a utility called "licensecheck" that will scan a directory and report the license used by each file. Chromium has a wrapper called "checklicenses.py" that checks the output of licensecheck against a list of incompatible licenses. If someone were to take the next step of letting you point checklicenses.py at a remote repository the world would be a better place.