Geopolitical rivals Saudi Arabia and Iran may be headed for another OPEC showdown, as the producer group enters negotiations over extending oil production cuts in force since January.  Saudi Arabia may demand that Iran, which is allowed a slight rise in output under the deal, commit to an output reduction as a condition of continuing the cuts, people familiar with the kingdom’s thinking told S&P Global Platts.  The provision is among several that Saudi Arabia, tired of seeing its market share eroded as it bears most of the burden of OPEC’s agreed cuts, is likely to come to the table with, sources say. These include stipulations on members who have exceeded their quotas and exempt members nearing full production capacity, notably Nigeria.