Prevent token refresh loop

app/src/main/java/eu/faircode/email/ServiceAuthenticator.java

@@ -136,7 +136,8 @@ public class ServiceAuthenticator extends Authenticator {
             Log.e(ex);
         }
 
-        if (expiration != null && expiration - keep_alive < new Date().getTime())
+        long slack = Math.min(keep_alive, 30 * 60 * 1000L);
+        if (expiration != null && expiration - slack < new Date().getTime())
             throw new IllegalStateException(Log.TOKEN_REFRESH_REQUIRED);
     }
 

app/src/main/java/eu/faircode/email/ServiceSynchronize.java

@@ -2005,7 +2005,8 @@ public class ServiceSynchronize extends ServiceBase implements SharedPreferences
                             }
 
                             // Check token expiration
-                            iservice.check();
+                            if (!account.isTransient(this))
+                                iservice.check();
 
                             // Sends store NOOP
                             if (EmailService.SEPARATE_STORE_CONNECTION) {