[geary] Fix error when adding third account. Bug 779048.

[Michael Gratton <mjog src gnome org>]

commit d4a95fa2876d7f196b16b2724fd851a4ed272920
Author: Michael James Gratton <mike vee net>
Date:   Thu Feb 23 11:27:39 2017 +1100

    Fix error when adding third account. Bug 779048.
    
    Patch courtesy of Rafał Masternak <rafdev muub net>

 src/engine/api/geary-engine.vala |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/engine/api/geary-engine.vala b/src/engine/api/geary-engine.vala
index faaf818..bd36ba2 100644
--- a/src/engine/api/geary-engine.vala
+++ b/src/engine/api/geary-engine.vala
@@ -279,7 +279,7 @@ public class Geary.Engine : BaseObject {
         string? last_account = this.accounts.keys.fold<string?>((next, last) => {
                 string? result = last;
                 if (next.has_prefix(ID_PREFIX)) {
-                    result = (last == null || strcmp(last, next) > 0) ? next : last;
+                    result = (last == null || strcmp(last, next) < 0) ? next : last;
                 }
                 return result;
             },