'Constant' variable guards dead code

A variable being assigned only once may be intentionally guarding disabled code, or it may represent incomplete logic where a missing assignment would make the variable not be constant. Variable assigned once to a constant guards dead code.
/src/mongo/db/write_concern.cpp:97: DEADCODE 119982 Assigning: "getLastErrorDefaultsWasApplied" = "false".
/src/mongo/db/write_concern.cpp:142: DEADCODE 119982 At condition "getLastErrorDefaultsWasApplied", the value of "getLastErrorDefaultsWasApplied" must be equal to 0.
/src/mongo/db/write_concern.cpp:142: DEADCODE 119982 The condition "getLastErrorDefaultsWasApplied" cannot be true.
/src/mongo/db/write_concern.cpp:143: DEADCODE 119982 Execution cannot reach the expression "provenance->setSource(boost::optional<mongo::ReadWriteConcernProvenanceSourceEnum>(mongo::ReadWriteConcernProvenanceSourceEnum(mongo::ReadWriteConcernProvenanceSourceEnum::getLastErrorDefaults)))" inside this statement: "provenance->setSource(boost...".