Fix disable_3pid_login being ignored for the email field (#11335)

src/components/views/auth/RegistrationForm.tsx

@@ -433,7 +433,8 @@ export default class RegistrationForm extends React.PureComponent<IProps, IState
     }
 
     private showEmail(): boolean {
-        if (!this.authStepIsUsed("m.login.email.identity")) {
+        const threePidLogin = !SdkConfig.get().disable_3pid_login;
+        if (!threePidLogin || !this.authStepIsUsed("m.login.email.identity")) {
             return false;
         }
         return true;