[geary: 2/3] Fix UpdateMailboxCommand to work correctly when there is only a single mailbox

[Michael Gratton <mjog src gnome org>]

commit 843c31db74b0227118baaf43fd67331270a5d0ad
Author: Kristian Klausen <kristian klausen dk>
Date:   Wed Feb 20 14:23:27 2019 +0100

    Fix UpdateMailboxCommand to work correctly when there is only a single mailbox
    
    This commit update UpdateMailboxCommand to use a new function
    ("replace_sender") to replace a existing mailbox, instead of
    remove/insert, which doesn't work if the number of mailboxes is 1.
    
    This fix two bugs (if number of mailboxes is 1):
    1. The "name" couldn't be updated.
    2. If you did change the address, the old mailbox wasn't removed.
    
    See also #226

 src/client/accounts/accounts-editor-edit-pane.vala | 6 ++----
 src/engine/api/geary-account-information.vala      | 7 +++++++
 2 files changed, 9 insertions(+), 4 deletions(-)
---
diff --git a/src/client/accounts/accounts-editor-edit-pane.vala 
b/src/client/accounts/accounts-editor-edit-pane.vala
index c64a8362..3576a53d 100644
--- a/src/client/accounts/accounts-editor-edit-pane.vala
+++ b/src/client/accounts/accounts-editor-edit-pane.vala
@@ -605,15 +605,13 @@ internal class Accounts.UpdateMailboxCommand : Application.Command {
 
     public async override void execute(GLib.Cancellable? cancellable) {
         this.row.mailbox = this.new_mailbox;
-        this.row.account.remove_sender(this.old_mailbox);
-        this.row.account.insert_sender(this.mailbox_index, this.new_mailbox);
+        this.row.account.replace_sender(this.mailbox_index, this.new_mailbox);
         this.row.account.changed();
     }
 
     public async override void undo(GLib.Cancellable? cancellable) {
         this.row.mailbox = this.old_mailbox;
-        this.row.account.remove_sender(this.new_mailbox);
-        this.row.account.insert_sender(this.mailbox_index, this.old_mailbox);
+        this.row.account.replace_sender(this.mailbox_index, this.old_mailbox);
         this.row.account.changed();
     }
 
diff --git a/src/engine/api/geary-account-information.vala b/src/engine/api/geary-account-information.vala
index a3e68016..4efeab59 100644
--- a/src/engine/api/geary-account-information.vala
+++ b/src/engine/api/geary-account-information.vala
@@ -356,6 +356,13 @@ public class Geary.AccountInformation : BaseObject {
     }
 
     /**
+     * Replace a mailbox at the specified index.
+     */
+    public void replace_sender(int index, Geary.RFC822.MailboxAddress mailbox) {
+        this.mailboxes.set(index, mailbox);
+    }
+
+     /**
      * Returns the configured path for a special folder type.
      *
      * This is used when Geary has found or created a special folder