scan-build "No bugs found."

I'm running scan-build on Apache Traffic Server and getting "No bugs found.", which isn't what I expect.

I ran it as follows:

   $ git clone GitHub - apache/trafficserver: Apache Traffic Server™ is a fast, scalable and extensible HTTP/1.1 and HTTP/2 compliant caching proxy server.
   $ cd trafficserver
   $ autoreconf -i
   $ ./configure
   $ scan-build -v -v make V=1 2>&1 > ~/Desktop/scan-build

Here's the output [1].

I didn't run ./configure through scan-build, but I conclude from the Make output that the compiler is being correctly interposed upon, so I shouldn't need to? The output indicates that the compiler is c++-analyzer.

The output contains lines like the following, so I conclude that the analyzer is working?

   ANALYZE (Syntax): ../../lib/ts/ink_mutex.h ~x_pthread_mutexattr_t

And it contains lines like "1 warning generated.", so I conclude that there should be bugs?

So my first question is, why are there "No bugs found."?

Also, although I redirect both stdout and stderr, the lines I mentioned -- "ANALYZE ..." and "1 warning generated." -- are nonetheless printed on the console, not [1]. Why is that?