interestingVariablesAreProperlyTracked

Solves p(A, B, C) against TestingClauseTheories.callsWithVariablesAndInspectorTheory's theory with it.unibo.tuprolog.solve.flags.TrackVariables on; the intermediate variable D (bound only inside the theory's own rule bodies, not directly by the query) is observed by the inspector at its fourth call site, alongside the query's own A/B/C/E — it is not discarded even though it is not one of the query's variables.