message: exit list more sanely on backspace
diff: @@ -572,8 +572,9 @@ export default class MessageComposerInput extends React.Component {
  if (this.state.isRichtextEnabled) {
  // let backspace exit lists
  const isList = this.hasBlock('list-item');
  - if (isList) {
  - const change = this.state.editorState.change();
  + const { editorState } = this.state;
  + if (isList && editorState.anchorOffset == 0) {
  + const change = editorState.change();
  change
  .setBlocks(DEFAULT_NODE)
  .unwrapBlock('bulleted-list')
  