Keep current primary account on import

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

@@ -762,6 +762,8 @@ public class ActivitySetup extends ActivityBase implements FragmentManager.OnBac
                         Log.i("Imported answer=" + answer.name + " id=" + answer.id + " (" + id + ")");
                     }
 
+                    EntityAccount primary = db.account().getPrimaryAccount();
+
                     // Accounts
                     JSONArray jaccounts = jimport.getJSONArray("accounts");
                     for (int a = 0; a < jaccounts.length(); a++) {
@@ -770,6 +772,9 @@ public class ActivitySetup extends ActivityBase implements FragmentManager.OnBac
                         Long aid = account.id;
                         account.id = null;
 
+                        if (primary != null)
+                            account.primary = false;
+
                         // Forward referenced
                         Long swipe_left = account.swipe_left;
                         Long swipe_right = account.swipe_right;