Walgreens says it will not start selling an abortion pill in 20 states that had warned of legal consequences if it did so.The drugstore chain’s announcement Thursday signals that access to mifepristone may not expand as broadly as federal regulators intended in January, when they finalized a rule change allowing more pharmacies to provide the pill.The U.S. Food and Drug Administration approved mifepristone in 2000 to end pregnancy, when used in combination with a second drug, misoprostol. The combination is approved …