maxh: Does _builder.py actually load the version of the fixture/ directory from the last-lts branch into the current python interpreter? I see some references to load_all_modules(). That seems kind of broken to me because the definition of LAST_LTS_MONGOD_BINARY is different between branches and means the default textual interpretation is wrong.
maxh: I feel like at least knowing that we're using the v5.0 version of the fixture/ directory with the v5.0 definition of LAST_LTS_MONGOD_BINARY in mongodb-mongo-master at least restores my sanity as to why the mongod-5.0 invocation is missing only receiveChunkWaitForRangeDeleterTimeoutMS and coordinateCommitReturnImmediatelyAfterPersistingDecision along with using DEFAULT_EVERGREEN_LAST_LTS_MONGOD_LOG_COMPONENT_VERBOSITY. Those are all the parameters which are controlled by self.config.LAST_LTS_MONGOD_BINARY.
maxh: Basically mongodb-mongo-master is accidentally configuring binVersion 5.0 as if it were mongodb-mongo-v5.0 configuring binVersion 4.4. Instead the design probably intended to configure binVersion 5.0 as if it were mongodb-mongo-v5.0 configuring binVersion 5.0 (aka latest from that Evergreen project's perspective).