MAGETWO-38302: Region field is absent in customer address form on backend for "United Kingdom" country.

Author: slopok

app/code/Magento/Customer/view/base/ui_component/customer_form.xml

@@ -429,7 +429,7 @@
                     <item name="dataType" xsi:type="string">text</item>
                     <item name="formElement" xsi:type="string">select</item>
                     <item name="source" xsi:type="string">address</item>
-                    <item name="customEntry" xsi:type="boolean">true</item>
+                    <item name="customEntry" xsi:type="string">region</item>
                     <item name="validation" xsi:type="array">
                         <item name="required-entry" xsi:type="boolean">true</item>
                     </item>