"This is a darn good question! The link to Cvs::Result::Log goes nowhere on CPAN, and there does not seem to be any reference to why the link is there but it's target is not."

See https://rt.cpan.org/Public/Bug/Display.html?id=15831:

"The log method does not seem to be implemented, however it is documented here:

http://search.cpan.org/~rsoliv/Cvs-0.07/lib/Cvs.pm#log

The Log.pm seems to be missing from the distribution."

Always check the issues queue, this was raised 9 years ago. The module has not been updated in 10 years.