message: Show the default IS as a placeholder in Settings
  This changes the UX for the set IS field to show the default IS as a placeholder
  value (as opposed to an initial value as if the user had actually entered it).
  Fixes
diff: @@ -95,8 +95,9 @@ export default class SetIdServer extends React.Component {
  }
  this.state = {
  + defaultIdServer,
  currentClientIdServer: MatrixClientPeg.get().getIdentityServerUrl(),
  - idServer: defaultIdServer,
  + idServer: "",
  error: null,
  busy: false,
  disconnectBusy: false,
  @@ -265,7 +266,10 @@ export default class SetIdServer extends React.Component {
  </span>
  <Field label={_t("Identity Server")}
  id="mx_SetIdServer_idServer"
  - type="text" value={this.state.idServer} autoComplete="off"
  + type="text"
  + autoComplete="off"
  + placeholder={this.state.defaultIdServer}
  + value={this.state.idServer}
  onChange={this._onIdentityServerChanged}
  tooltipContent={this._getTooltip()}
  />
  