[$] Bugs and fixes in the kernel history

Each new kernel release fixes a lot of bugs, but each release also
introduces new bugs of its own. That leads to a fundamental
question: is the kernel community fixing bugs more quickly than it is adding
them? The answer is less than obvious but, if it could be found, it
would give an important indication of the long-term future of the kernel
code base. While digging into the kernel's revision history cannot give a
definitive answer to that question, it can provide some hints as to what
that answer might be.