An alkyne (R-CC-R|) when treated with KMnO4 in neutral medium gives diketone (R-CO - CO-R|.
even if some heat is provided or acquired, it will consequently break to form carboxyilic acids to give (RCOOH and R|COOH). So yeah, it's true that a diketone compound formed after oxidation and breaks further in hot KMnO4.