it was reported that -DWITH_SSL=yes helps to avoid ssl compilation problems, by forcing bundled yassl, instead of system ssl library

Actually, the goal is the opposite. You must use -DWITH_SSL=yes to avoid the bundled yaSSL. It may be better to use -DWITH_SSL=system if no solution can be found to yaSSL problems on OS X so that cmake can abort configuration in the case of no available system SSL instead of leaving the failure to the end of the build process.

after changing the buildbot config labrador builds started failing all tests, it took some time to track it down