Set Select2 height to the height of normal input fields.

interface/web/themes/default/assets/stylesheets/select2.css

@@ -27,14 +27,14 @@ Version: 3.5.2 Timestamp: Sat Nov  1 14:43:36 EDT 2014
 
 .select2-container .select2-choice {
     display: block;
-    height: 26px;
+    height: 32px;
     padding: 0 0 0 8px;
     overflow: hidden;
     position: relative;
 
     border: 1px solid #aaa;
     white-space: nowrap;
-    line-height: 26px;
+    line-height: 32px;
     color: #444;
     text-decoration: none;